In the past decade, genetic testing aimed at identifying ancestry has experienced exponential growth, with nearly 26 million tests sold since 2018 (6). Companies – such as 23andMe – offer kits to trace your genetic legacy and geographical origins using Y-chromosome, mitochondrial, and whole-genome markers (1). Genetic ancestry testing holds the potential to identify the geographic origins of an individual’s ancestors, ancestral lineages, and relatives, but does not define a deterministic cultural identity.
DNA located in the mitochondrion, mtDNA, is inherited maternally in both sexes and can thus provide evidence of an direct, unbroken female lineage (10). The mtDNA typically passes unchanged from mother to offspring, except in the rare case of a mutation. By comparing full mtDNA sequence or assaying for particular haplogroups, it is possible to establish both close ancestry and rough global origins, respectively (4). Regardless, two individuals, even with an exact mtDNA match, may have had an ancestor as far back as ten or sixteen generations (9). Consumers should thus be warned against over-interpreting mtDNA results since they unravel a single thread in an individual’s genetic ancestry. A distinct benefit of mtDNA tests is the ability to distinguish maternal lineage in recorded genealogical data in which females adopt the male surname (10).
Contrary to mtDNA, Y-chromosome DNA is inherited paternally, passed down from father to son. Ancestry tests analyze locations along the Y chromosome, cataloging mutations known as single nucleotide polymorphisms and repeating patterns known as short tandem repeats (8). Test results can determine if two male members of separate families with the same surname have a close genetic relationship (10). In addition, a multitude of haplogroups, representing branching in the Y-chromosome tree, can be used to examine the presence of a common ancestor thousands of years back, contributing another thread to the central question of genetic ancestry (8,7).
A more comprehensive basis of determining ancestry relies on the presence of millions of autosomal variants, such as single nucleotide variants (SNVs), across the genome (10,3,7). An individual’s unique pattern of SNVs is compared with various reference populations and other consumers in order to infer their ancestry (10). Companies such as 23andMe provide a readout of broad ancestry and specific subgroups. Ancestral populations such as European and Western Asian are often further broken down into subpopulations (e.g. British, Greek, Iran). The accuracy of more specific statistical inferences is often variable, with companies examining different SNVs reporting inconsistencies in percentages for the same individual (3). In addition, since many reference populations do not account for migration and interbreeding thousands of years back, an ethnicity estimate with a high degree of confidence could still differ drastically from an individual’s expectations (10). Statistical inferences have diminished accuracy in regions such as East Africa and South Asia with comparatively limited data relative to well studied European populations, leading to further possible inconsistencies (7).
While the commercialization of genetic-ancestry tests has resulted in improved accuracy and innovation, the hyper-aggressive marketing of such products risks misinforming consumers, particularly in regards to cultural heritage. Consider, for example, an advertisement by the company Ancestry where a woman finds “[her] strength” after realizing she shares maternal lineage to a matriarchal people in Ghana (11). The pervasive marketing has even infiltrated music: In 2018, Spotify and Ancestry partnered to suggest playlists and artists based on test results, blatantly equating DNA and cultural heritage (2). While such marketing efforts are externally harmless, they carry a hidden message that DNA plays a meaningful role in our cultural identity. Most consumers are ill-informed in the field of genomic science, and may assume that their test results are deterministic and connote a contribution to heritage.
Genetic-ancestry tests may also perpetuate the idea of innate racial differences and entangle race with culture. A randomized trial reported that White Americans with lower genetic literacy had increased essentialist views after receiving test results (6). Those of Hispanic heritage share cultural aspects such as language, but may differ in genetic test results due to post-colonial admixture of Native, European, and African populations (5). Does a test result of 90% European heritage indicate “more” Hispanic heritage than 80% African? Such conclusions are entirely inaccurate and dangerous, but plausible given the genetic literacy of the typical consumer.
Cultural identity is a conglomerate of an immeasurable amount of connections including family traditions, languages, and food. Genetic-ancestry tests may motivate an individual to seek out connections and explore other cultures, but they are in no way an absolute determinant for identity.
1. Callaway, E. (2012, June 6). Ancestry testing goes for pinpoint accuracy. Retrieved March 4, 2020, from https://www.nature.com/news/ancestry-testing-goes-for-pinpoint-accuracy-1.10785
2. Hassan, A. (2018, September 24). Spotify and Ancestry can use your real DNA to tell your “musical DNA”. Retrieved March 4, 2020, from https://qz.com/quartzy/1399279/spotify-can-use-your-ancestry-dna-test-to-tell-your-musical-dna/
3. Jorde LB, Bamshad MJ. Genetic Ancestry Testing: What Is It and Why Is It Important? JAMA. Published online February 14, 2020. doi:10.1001/jama.2020.0517
4. Kivisild T. (2015). Maternal ancestry and population history from whole mitochondrial genomes. Investigative genetics, 6, 3. https://doi.org/10.1186/s13323-015-0022-2
5. Lao, O., Vallone, P. M., Coble, M. D., Diegoli, T. M., van Oven, M., van der Gaag, K. J., Pijpe, J., de Knijff, P., & Kayser, M. (2010). Evaluating self-declared ancestry of U.S. Americans with autosomal, Y-chromosomal and mitochondrial DNA. Human mutation, 31(12), E1875–E1893. https://doi.org/10.1002/humu.21366
6. Roth, W. D., Yaylacı, Ş., Jaffe, K., & Richardson, L. (2020). Do genetic ancestry tests increase racial essentialism? Findings from a randomized controlled trial. PloS one, 15(1), e0227399. https://doi.org/10.1371/journal.pone.0227399
7. Royal, C. D., Novembre, J., Fullerton, S. M., Goldstein, D. B., Long, J. C., Bamshad, M. J., & Clark, A. G. (2010). Inferring genetic ancestry: opportunities, challenges, and implications. American journal of human genetics, 86(5), 661–673. https://doi.org/10.1016/j.ajhg.2010.03.011
8. Wayne, D. P. Using Y-DNA for Genealogy. National Genealogical Society NGS Magazine, x40 (January-March 2014), 20-24.
9. Wayne, D. P. Using mitochondrial DNA for Genealogy. National Genealogical Society NGS Magazine, 39 (October-December 2013), 26-30
10. What is genetic ancestry testing? – Genetics Home Reference – NIH. (2020, March 3). Retrieved March 4, 2020, from https://ghr.nlm.nih.gov/primer/dtcgenetictesting/ancestrytesting
11. Zhang, S. (2018, September 26). Your DNA Is Not Your Culture. Retrieved March 4, 2020, from https://www.theatlantic.com/science/archive/2018/09/your-dna-is-not-your-culture/571150
In 2003, a group of international researchers announced the completion of the Human Genome Project, a massive undertaking with the aim of mapping the full genomic sequence of human DNA (1). Since then, the rapidly falling time and cost requirements for sequencing have led to the prevalence of DTC (direct-to-consumer) DNA testing, a rapidly-growing industry now worth upwards of $1 billion (2). Today, genetic testing is often used to determine health information such as whether the test taker is a carrier for certain disease-causing genes. Another controversial but frequently-advertised aspect of DTC testing services is the ability to determine the ethnic origins of the person taking the test (3). Although ancestry testing may provide insight on an individual’s genetic background, those taking a genetic test should seek to use this information to supplement rather than replace cultural and family traditions in determining their identity.
Several sources of genetic material can be analyzed for testing, such as Y chromosomal DNA, mitochondrial DNA, and autosomal DNA. In lineage-based testing, mitochondrial dna (mtDNA), which is inherited through the mother, and Y chromosomal DNA, which is inherited through the father, are analyzed to trace an individual’s maternal and paternal lineage respectively (4). However, since Y chromosomal DNA and mtDNA only account for a small subset of genetic ancestry, they become increasingly unrepresentative of an individual’s genetic makeup when tracing older generations: although each ancestor has contributed equally to an individual’s genetic information, they only share Y chromosomal DNA or mtDNA with one of two parents, one of four grandparents, one of eight great-grandparents, and so on (4).
In an effort to offer more accurate ancestry testing, industry focus has shifted from lineage-based testing to analysis of data from the 22 autosomal chromosomes (1), where patterns of certain genetic sequences known as ancestry-informative markers (AIMs) are used to infer the overall ethnic makeup of the test taker (4). While providing a less incomplete picture of ancestry than lineage-based testing, AIM patterns are still drawn from a sample size that is far from representative, especially for minority groups. For example, in a genomic analysis from the DTC testing company 23andMe, only three percent of the 160,000 subjects were of African descent (6). While the company claims that its tests are “well-calibrated” (6) despite a small sample size, this shallow genetic sample of a few thousand individuals does not reflect the ethnic and cultural diversity of the people living in African continent.
Although it can be concluded that ancestry tests are far from an authoritative source for determining the complexities of many individuals’ genetic ancestry, they are certainly not advertised as such. In a particularly egregious example of advertising from the DTC testing company AncestryDNA, a man who was raised with German traditions changes his cultural practices after learning that he has Scottish DNA, saying that “traded in [his] lederhosen for a kilt” (1). Although endearing, this advertisement ignores the fact that cultural traditions are not contained within the genome, coming instead from factors such as upbringing, nationality, and family background. By conflating ethnicity with culture, AncestryDNA’s marketing promotes a narrow definition of ancestry based only on genetics, one that fringe groups such as white supremacists have co-opted with the pseudoscientific idea of “genetic essentialism,” where a person’s mental and physical abilities allegedly depend solely on one’s genetic ancestry (2). Surprisingly, a University of British Columbia study found that after taking a genetic test, those with little genetic knowledge increased their beliefs in genetic essentialism, while those with prior genetic knowledge decreased their essentialist beliefs (2). Thus, it is crucial that DTC testing companies inform prospective customers of the influence of societal factors in addition to genetic ancestry on one’s cultural identity in order to avoid promoting an essentialist definition of genetics with their advertising.
Although DTC genetic testing may appeal to the desire to learn about one’s genetic history and have potential uses in health, its flaws must also be acknowledged. In addition to the unrepresentative nature of the tests themselves, it is important to consider that such a personal issue as cultural identity is also based on a host of socioeconomic factors, including religion, class, and nationality. In conclusion, it is critical to combat the rise of misinformation surrounding genetic testing, in no small part the result of growing distrust in political and scientific institutions. Without arming people with knowledge of the diverse elements that determine their identity, ancestry testing may serve to increase divides rather than facilitate understanding between ethnic groups in society.
Scodari, C. (2017). When Markers Meet Marketing: Ethnicity, Race, Hybridity, and Kinship in Genetic Genealogy Television Advertising. Genealogy, 1(4): 22. doi: 10.3390/genealogy1040022
Roth W. D., Yaylacı Ş., Jaffe K., & Richardson L. (2020). Do genetic ancestry tests increase racial essentialism? Findings from a randomized controlled trial. PLOS One, 15(1): e0227399. doi: /10.1371/journal.pone.0227399
Phillips, A. M. (2016). Only a click away — DTC genetics for ancestry, health, love… and more: A view of the business and regulatory landscape. Applied & Translational Genomics, 8: 16-22. doi: 10.1016/j.atg.2016.01.001
Duster, T. (2014). Ancestry testing and DNA: Uses, limits — and caveat emptor. In B. Prainsack, G. Werner-Felmayer, S. Schicktanz (Eds.), Genetics as social practice: transdisciplinary views on science and culture (pp. 59-72). Ashgate.
Bryc, K., Durand, E. Y., Macpherson, J. M., Reich, D., & Mountain, J. L. (2015). The genetic ancestry of African Americans, Latinos, and European Americans across the United States. American Journal of Human Genetics, 96(1): 37–53. doi: 10.1016/j.ajhg.2014.11.010
Advancements in genomic sequencing have given rise to ancestry-based direct-to-consumer genetic tests (DTC-GTs), at-home profiling services which examine genetic variation patterns within salivary DNA samples to estimate aspects of biologically-based origin . Genetic ancestry is frequently conflated with cultural heritage, particularly in the context of DTC-GT results; although such correlations are present in some groups, oversimplifications equating the two concepts are incorrect.
Three genetic marker systems are employed for ancestry estimation, each marker contributing varying insights [2, 3]. Autosomal DNA (atDNA) tests utilize datasets of autosomal single nucleotide polymorphisms (SNPs) and other ancestry-informative markers sampled from current geographic subpopulations serving as proxies for ancestral parental demes [3, 4]. Comparison of these reference samples to consumer DNA yields admixture and biogeographic ancestry (BGA) estimations and identifies biological relatives with common ancestors within the last six generations [3, 4]. Y-chromosomal DNA (Y-DNA) and mitochondrial DNA (mtDNA) are uniparental haploid loci following nonrecombinant clonal inheritance patterns, with the former reflecting direct patrilineal ancestry and latter encompassing direct matrilineal ancestry [5, 6]. Y-DNA testing analyzes Y haplogroup (hg)-differentiating Y-SNP and Y-chromosomal short tandem repeat (Y-STR) polymorphisms to reveal samples’ Y-hgs and estimate hg-predictive paternal BGA . Similarly, mtDNA DTC-GTs track mt-SNPs and coding hypervariable region (HVRI and HVRII) mutations for mt-hg and maternal BGA information [6, 7]. Further haplotype similarity analyses infer genealogical relationships and degrees of relatedness along patri- and matri-lines [1, 8].
The genetic knowledge consumers gain through atDNA, mtDNA, and Y-DNA DTC-GTs are valid biological measures of identity. However, a perception exists that genetic ancestry is deterministic of the cultural aspects of identity; marketing language such as “Discover Yourself”  and “Reinvent the way you see yourself”  further perpetuate the biological ingrainedness of cultural heritage through promises of identity “meaning-making” , leading to concerns that consumers may adjust their cultural heritages to align with “true” DTC-GT-informed origin. Indeed, literature has documented changes in consumer interpretations of cultural and family histories [12, 13] and claims of membership in communities (ex. indigenous tribes) [1, 3, 12] due to newfound genetic origins. This pinpointing of core identity as primarily derived from biological ancestry rather than the cultural narratives behind that identity is “problematic at best and harmful at worst” .
UNESCO defines cultural heritage as expressions which play significant, self-established roles in their bearers’ cultural identities and socially-mediated evolution of those expressions [15, 16]: social groups are maintained within cultural and historical, rather than biological, contexts, with the cultural heritage of a cluster- an individual, family, or other unity- being the shared practices, values, knowledge, and traditions which bearers self-identify with and which are modified in parallel to environmental transformations . In traditional environments with fixed social boundaries and little social evolution, cultural traits were more likely to be transmitted vertically through genetically related generations, with groups maintaining largely unvarying cultural heritages and identities [17, 18]. Over long periods, these culturally isolated groups may display increased cultural distinctiveness and identifiable allelic similarities, with cultural traits showing correlation with genetic ancestry. Indeed, the cultures which some identify with are shared by their ancestral groups, by present-day populations geographically representative of their ancestors, or by genetically similar individuals.
However, more prominent horizontal cultural exchanges and cultural drift within generations in the contemporary age through globalization have caused clusters to come in increased contact with other evolving, unfamiliar cultural behaviors and experiences . This deepening and widening interconnectedness facilitates constant recreations in individuals’ identities and group affiliations (ex. adoption of new traditions, technologies, and ways of living). Through exposure to shifting social conditions, genomically divergent clusters may share common cultural heritages, while individuals displaying higher levels of genetic homogeneity may hold greatly differing interpretations of heritage and cultural identity. Individuals, by interacting with their surroundings, construct their own interpretations of cultural heritage which inform their cultural identity. Assuming the existence of genetically-determined cultural heritage overlooks these personal and social influences, as well as the dynamicity and unpredictability, of the entity. Therefore, cultural heritage is unable to be definitively captured by biological markers, among them BGA and admixture estimates.
Individuals are mixtures of biological and cultural characteristics; there is value in recognizing both contributions to identity and origin, especially when addressing health disparities . Correlations between ancestry-informative genomic variability and self-identified cultural identity exist in many clusters; however, the unpredictable connection between the two, due to the fluidity of perceived cultural heritage and the social exchanges exacerbating its complexity, shows that genetic ancestry information provided by DTC-GTs cannot viably determine or be equated with cultural heritage.
1.Jobling, M. A., Rasteiro, R., & Wetton, J. H. (2016). In the blood: the myth and reality of genetic markers of identity. Ethnic and Racial Studies, 39(2), 142-161.
- Dutheil J.Y., & Hobolth A. (2019). Ancestral population genomics. In M. Anisimova (Eds.). Evolutionary Genomics (pp. 555-589). New York, NY: Humana.
- Royal, C. D., Novembre, J., Fullerton, S. M., Goldstein, D. B., Long, J. C., Bamshad, M. J., & Clark, A. G. (2010). Inferring genetic ancestry: opportunities, challenges, and implications. The American Journal of Human Genetics, 86(5), 661-673.
- Kirkpatrick, B. E., & Rashkin, M. D. (2017). Ancestry testing and the practice of genetic counseling. Journal of Genetic Counseling, 26(1), 6-20.
- Prestes, P. R., Mitchell, R. J., Daniel, R., Sanchez, J. J., & van Oorschot, R. A. (2016). Predicting biogeographical ancestry in admixed individuals–values and limitations of using uniparental and autosomal markers. Australian Journal of Forensic Sciences, 48(1), 10-23.
- Calafell, F., & Larmuseau, M. H. (2017). The Y chromosome as the most popular marker in genetic genealogy benefits interdisciplinary research. Human Genetics, 136(5), 559-573.
- Pipek, O. A., Medgyes-Horváth, A., Dobos, L., Stéger, J., Szalai-Gindl, J., Visontai, D., … & Csabai, I. (2019). Worldwide human mitochondrial haplogroup distribution from urban sewage. Scientific Reports, 9(1), 1-9.
- Torres, J. B. (2016). A history of you, me, and humanity: mitochondrial DNA in anthropological research. AIMS Genetics, 3(2), 146.
- dynamicdnalabs.com (2020). Home health tests. Retrieved from https://dynamicdnalabs.com/. Accessed March 2, 2020.
- crigenetics.com (2020). DNA testing for ancestry home DNA test kit. Retrieved from https://www.crigenetics.com/. Accessed March 2, 2020.
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- Walajahi, H., Wilson, D. R., & Hull, S. C. (2019). Constructing identities: the implications of DTC ancestry testing for tribal communities. Genetics in Medicine, 21(8), 1744-1750.
- Roth, W. D., & Ivemark, B. (2018). Genetic options: The impact of genetic ancestry testing on consumers’ racial and ethnic identities. American Journal of Sociology, 124(1), 150-184.
- Yudell, M., Roberts, D., DeSalle, R., & Tishkoff, S. (2016). Taking race out of human genetics. Science, 351(6273), 564-565.
- Lenzerini, F. (2011). Intangible cultural heritage: The living culture of peoples. European Journal of International Law, 22(1), 101-120.
- UNESCO (2003). Convention for the safeguarding of the intangible cultural heritage. Retrieved from http://portal.unesco.org/en/ev.php-URL_ID=17716&URL_DO=DO_TOPIC&URL_SECTION=201.html. Accessed March 2, 2020.
- Gorodnichenko, Y., Roland, G., Hauk, E., Immordino, G., Dohmen, T., Falk, A., … & Sunde, U (2015). Ancestry and Culture. Retrieved from https://voxeu.org/article/ancestry-and-culture, Accessed March 2, 2020.
- Boyd, R., & Richerson, P. J. (1988). Culture and the Evolutionary Process. Chicago, IL: University of Chicago Press.
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99.9% of human DNA is identical, leaving just 0.1% subject to variation. Ironically, genetic ancestry testing is contingent on this variation and is designed to inform people about their genealogies through examining miniscule DNA differences. Today, there are three common genetic ancestry tests: Y-DNA, Mitochondrial (Mt) DNA, and autosomal DNA tests . While these tests might prove useful for those interested in family history, they may wreak havoc on the construct of “self,” defined to be a combination of both self-perception and self-projection . Ultimately, the value of these tests lies with consumers and how they choose to integrate the results with their cultural identities.
Each genetic test relies on varying aspects of the genome. The Y-DNA test allows a male to trace his patrilineal heritage by comparing STR (short tandem repeat) markers to ones in a racially diverse database. This method allows one to uncover his haplogroup, an ancient group of people from which he descends. On the other hand, MtDNA tests trace any person’s matrilineal heritage through sequencing of mitochondrial DNA , genetic material present in both males and females. Unfortunately, both MtDNA and Y-DNA tests have limited ability in identifying ancestors because they trace genetic lines on a family tree with branches that double each generation. In other words, Y chromosome testing will link a man to one of four grandparents and one of eight great grandparents, and so on and so forth until 14 generations pass (meaning 16383 ancestors of equal relation are not identified) [3,4]. Critics fear that extrapolating this information to make conclusions about biogeographical ancestry is an error prone process, stating that one can only use genetic matches to verify common ancestry . Fortunately there exists another test that is more reliable and comprehensive: the autosomal DNA test.
Like MtDNA tests, autosomal DNA tests are unisex and trace autosomal chromosomes that contain common DNA segments between test subjects and ancestors. However, unlike the aforementioned tests, the autosomal DNA test will not provide information about one’s haplogroup . Rather, it is better used for information such as ethnicity percentages and close relationships because it tests SNPs (single nucleotide polymorphisms) on a much greater proportion of genome history, relying on multiple biparentally-inherited loci versus one . Evidently, performing all three tests would yield knowledge about one’s haplogroup, patrilineal and matrilineal heritage, ethnicity, and relationship to family members. More importantly, it would necessitate coming to terms with information that could jeopardize the construct of “self” and any and all identity claims.
The likelihood of one gaining information that directly contradicts with predetermined notions of “self” is very high, for a number of reasons. The reliability of these tests are questionable and depend on the diversity of the database from which DNA samples are being compared against. If the database population is skewed, the results will be inaccurate, seen in numerous cases in which consumers report conflicting results from various testing companies . In the event that the tests sharply contrast with one’s established ancestral knowledge, an identity crisis may result. Nonetheless, there exist cases where genetic testing’s transformative power has benefitted populations and corroborated cultural traditions that remained otherwise unexplained.
Such was the case with the Lemba, a Bantu-speaking tribe from Africa that practiced Judaic rituals without any evidence of ancestral connection to Jews. Enduring years of ridicule for practicing circumcision, keeping one day a week holy, and avoiding pork , the tribe had their traditions validated by a group of geneticists. A Y-DNA test revealed that the Lemba men carry DNA sequences characteristic of some Jewish priests descended from Aaron [7,8]. Furthermore, the genetic signature shared in common between the two groups is rare or absent in non-Jewish populations , suggesting that the Lemba’s cultural heritage is strongly supported by genetics.
While the Lembas received their closure, many who take a DNA test are faced with piecing together their identity once more when test results contradict with cultural heritage. Chana Garcia lived her entire life believing she was Hispanic, proud of her Spanish speaking abilities. When the test results arrived, she was shocked to learn that she had no hispanic roots . Her conflict is indicative of the “human search for belonging” , something that genetic testing has the power to revolutionize immensely….for better or for worse. Thus, realizing that identity is a combination of multiple factors beyond just STR and SNP similarities is critical for bridging the gap between genetic ancestry test results and one’s cultural heritage.
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 Scodari, Christine. Alternate Roots: Ethnicity, Race, and Identity in Genealogy Media. University Press of Mississippi, 2018. JSTOR, www.jstor.org/stable/j.ctv5jxp62.
To explore their genealogy, the modern consumer often turns to ancestry testing, in which their genomic sequence is matched with genetic patterns of different ethnic populations. The results of such testing can be unexpected or inconsistent with one’s own perception of their familial history as unknown biological information, such as paternity, is brought to light. Thus, ancestry testing allows one to discover more about one’s personal identity. As one’s personal identity is integral to their perception of cultural heritage, ancestry testing therefore has the potential to reshape cultural awareness.
The first ancestry test, the Y chromosome test, traces paternal genealogy using DNA fingerprinting techniques (1,3). It is made possible by the specialized function of the Y chromosome in determining gender-specific development during embryogenesis, the chromosome’s non-recombination properties, and its strictly paternal inheritance (1). Consumers commonly take this test to determine relationships between ancestral lines with the same surname and to confirm or to trace their paternity (1,3).
Less than ten percent of the time (2), however, the results of the Y chromosome test uncover a discrepancy between the subject’s lifelong and biological father. Such a drastic discovery can not only upset existing social structure within families by evoking suspicion and insecurity, but can also cause testers to experience an existential crisis in which they question their previous identity. As each member of the family struggles to cope and redefine their personal identities, their cultural identities may become adjusted to reflect their new emotional situation.
To discern matrilineal heritage, on the other hand, one would turn to mitochondrial DNA (mtDNA) testing. MtDNA’s non-recombination, elevated mutation rate relative to nuclear DNA, and matrilineal inheritance, make it a desirable medium for genetic comparison (4,5) in matrilineal ancestry. This test is especially beneficial in tracing female ancestors that may have become lost over time due to the passing down of married and family surnames (5). It can additionally predict the probability of mitochondrial disease, particularly heteroplasmy, the co-existence of multiple DNA variants (4,6). As heteroplasmic mtDNA can cause physiological, cognitive and behavioral consequences (6), its discovery in a familial line could alter tester’s personal identity and lead to negative shift in the way they approach their cultural heritage.
From a cultural standpoint, the results of the mtDNA test may not carry the same weight on one’s identity as a Y chromosome test would, as illegitimacy is often associated with a biological father rather than a biological mother. An mtDNA test would like affirm one’s existing beliefs regarding one’s mother. Nevertheless, it is possible that an unknown female ancestor is discovered to be of an ethnicity previously unassociated with a family. In this situation, family members may choose to explore new ethnic traditions and merge those ideas with their existing family traditions to embrace their multicultural heritage.
Of the three ancestry tests, autosomal DNA (atDNA) testing is assuredly the most influential on a tester’s cultural heritage, because it can trace ancestry from both parents (7,8). As a child inherits equal percentages of their autosomal DNA from their parents, this test evaluates the extent of a patron’s genetic connection with ethnic populations based on the amount of single nucleotide polymorphisms (SNPs) shared on the twenty-two autosomal chromosomes (7). Information revealed by such testing includes recent lineage, long-term ancestry and migration, as well as an estimate of a person’s ethnic background (7,8). SNP sequences, for example, might divulge that a patron’s ancestry is sixty-three percent European, twenty-four percent Asian, and thirteen percent African. If such percentages were previously unbeknownst to the tester, the new discovery may prompt further pursual of their Asian descent or further research into the cultural norms of their African heritage. The concepts and traditions found may contrast with their existing familial customs, and thus, a new cultural identity may be formed. On the other hand, if the results of autosomal DNA testing proved one’s preconceived ethnic ancestry, one’s cultural heritage might be affirmed and the question of further action may prove unfounded.
All the ancestry tests described above will aid patrons in discovering more about their genetic inheritance, and with new understanding of one’s genetic inheritance comes an inevitable shift in one’s own personal identity. As one’s values of tradition are both contrasted and affirmed by new information, bonds are formed to bridge individuals with communities. Ultimately, preconceived notions of cultural heritage are adapted and merged with new findings to create entirely unique personal and cultural identities.
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As genetic testing has become cheaper, easier, and more readily available, many more people have begun using genetic tests to learn about their heritage and health. But what information can these tests provide? Through Y-chromosomal, mitochondrial, and autosomal DNA testing, a person could discover if he or she was predisposed to certain genetically-correlated health conditions, and determine how his or her genetic composition compares to that of various geographic populations. Yet, this information cannot always predict ethnicity or culture; though certain cultural practices may be common within various populations, emigrants from a region may not still practice their historical culture.
Autosomal, Y-chromosomal, and mitochondrial DNA testing are the three main types of genetic testing provided by direct-to-consumer companies (9), which market at-home testing to the public. Autosomal genetic testing refers to the testing of all non-sex chromosomes in the human genome. Mutations in autosomal DNA may put a person at increased risk for genetic diseases. For example, Huntington’s Disease (6), a progressive neural disorder which leads to loss of muscle control and cognitive ability, is caused by a mutation in the HTT gene. Risk of breast cancer is greatly increased by a mutation in the BRCA1 or BRCA2 gene (4). An autosomal DNA test could find these mutations and warn of the increased genetic risk of disease. Harmless variations in autosomal DNA, which are evaluated by a single nucleotide polymorphism test, can help determine ancestry because some variations are more common in certain geographical populations than others (10). Y-Chromosomal DNA testing traces a male’s patrilineal ancestry by analyzing the Y-chromosome, which remains nearly unchanged as it is passed from father to son. If two males have identical Y-chromosomes, they are likely descended from a common ancestor (7). Since females do not have a Y-chromosome, they cannot use this test. In contrast, males and females can both test their mitochondrial DNA since mitochondria are found in many cells throughout the body in both sexes. Mitochondrial DNA is inherited matrilineally, so mitochondrial DNA tests can be used to determine matrilineal heritage. This is especially useful to genealogists; surnames are often passed down patrilineally, so another method is sometimes needed to determine matrilineal lineage (10).
Many at-home genetic testing sites such as 23andMe and Ancestry.com claim to uncover a test taker’s family history by ascertaining where their ancestors originated from (1)(2). But how accurate is this claim, and how well can genetics predict culture? Since the dawn of man, people have been migrating to new places. Testing sites compare a person’s DNA to a database, connecting it to groups that have similar polymorphisms in order to determine heritage; this should prevent genealogical mistakes due to a person’s relatives migrating. However, the company’s assessment of lineage can only be as good as its database. For underrepresented groups such as people of African descent, the data pool is smaller and the results are less accurate, causing ancestry testing results to often be less specific than they would be for better represented groups (3). Additionally, the cultural effects of immigration sometimes cause ethnicity to become divorced from genetic heritage. In the United States, the population is only .9% Native American; the rest is comprised of immigrants (8). Though some immigrants may retain cultural practices from their country of origin, many instead assimilate. Marriage between people of different ethnicities can also be a complicating factor. For example, my grandfather immigrated to the US in 1958 from Bangalore. He married an American woman of European descent and had four children, including my mother. My mother and her sister both married European-American men. Theoretically, therefore, I should have a similar genetic makeup to my aunt’s children. Yet, we were raised in different cultural environments. I was raised immersed in American culture with few other cultural influences, while my cousins were raised with much more Indian cultural influence. This is because my aunt’s family lives in the same part of the country as many of our Indian relatives who immigrated more recently to the US, so they were more connected to that part of our familial culture than I was having grown up farther away. Therefore, it was happenstance and personal choices that led to the cultural differences within my family, not genetics.
Genetic testing will likely continue to be used for health and genealogical purposes. Yet, as the U.S. population becomes more racially and ethnically mixed (5), situations like my family’s will become increasingly common, further weakening the ability of genetic testing to predict culture.
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Ancestry testing leverages the naturally occurring evolutionary process of the biological system; environmental pressures or cell-intrinsic infidelity of the DNA replication and repair mechanisms can cause variations in the human genome . One such variation often used for ancestry testing is the single nucleotide polymorphism (SNP)—a single nucleotide substitution often observed with over 1% frequency in the population in the non-coding region of the genome . Numerous SNPs are inherited through generations and creates patterns unique to each subpopulation from different geographical regions, which can be documented and compiled into a reference library. An individual’s SNP profile can thus be compared to the SNP reference library to predict genetic heritage . While such tests of ancestry can offer insight into one’s genealogical backgrounds, their results must be carefully interpreted with an understanding that information from ancestry testing may be qualitatively different from one’s cultural heritage.
Three common ancestry tests are the Y chromosome, mitochondrial DNA, and autosomal DNA testing. Although all three converge on the usage of markers such as SNPs to trace ancestral information , they differ from one another in what distinct parts of the human DNA are utilized. If a person were to perform all three tests, each test will provide slightly different types of discrete genealogical information.
The Y chromosome is a sex chromosome that is strictly inherited from father to son. This male-specific segregation pattern of Y chromosome inheritance permits males to easily trace paternal lineage with high precision and accuracy through Y chromosome testing . On the other hand, mitochondrial DNA testing is strictly used to trace the maternal lineage . Mitochondria, the cell’s primary energy source, have their own genome independent of the
genome inside the nucleus. Mitochondrial DNA is unequivocally passed down through maternal lineage since oocytes preserve mitochondria in the early embryonic development while those in the spermatozoa are lost in the process . Thus, mitochondrial DNA enables us to trace our maternal lineage. While these two tests offer unique information on sex-specific ancestral lineage, autosomal chromosome testing offers more comprehensive genealogical background information. Autosomal chromosomes refer to the 22 non-sex chromosomes inherited from both parents . Unlike mitochondrial DNA or Y chromosome, which are not subject to recombination [4, 6], autosomal chromosomes recombine, segregate, and rearrange as germline cells go through DNA replication, division, and fertilization, respectively. This process leaves behind genealogically informative traces throughout the numerous SNP-rich regions within autosomal chromosomes. Using this global approach, different combinations of SNPs and their rate of incidence are taken into consideration in determining one’s genetic heritage .
Individuals strive to learn about themselves through the pursuit of deeper knowledge regarding their identity, and this process could begin with learning about one’s roots. Ancestry tests can collectively provide information about genetic heritage; however, this is only a fraction of one’s identity. Just like genetic heritage, cultural heritage is another type of information that gets passed down intergenerationally that comprises one’s identity. Cultural heritage refers to all elements of culture that gets transmitted to individuals through their families/guardians, teachers, and the broader community and society . The elements of “inheritable culture” vary widely, and include factors such as values, beliefs, skills, and behavioral traditions [8, 9].
The genealogical history of individuals and their cultural heritage share that they both
involve the intergenerational transmission of some properties and information that can shape and define a person. The key difference between cultural and genetic heritage, however, is the nature of this transmission. Genetic information is vertically and unidirectionally transferred from generation to generation. This information cannot be modified by the social and environmental circumstances of individuals during their lifetime. On the other hand, cultural information from older generations are acquired by the younger generations through ways such as behavioral conditioning, imitation, and replication, as well as active teaching and learning. This makes cultural transmission a variable process. The nature of individuals’ social interactions with others, and the situational factors that shape those interactions, can impact the degree to which cultural transmission happens . Because of this difference in the mode of transmission, a person’s genetic ancestry may include traces of a certain subpopulation, whose culture may not necessarily constitute his/her cultural heritage.
In all, cultural ancestry is a distinctive property that could, in many parts, differ from one’s biogeographical ancestry. Because of these distinctions, however, deeper knowledge about both our genetic and cultural heritage can offer us not only mutually complementing but also synergistic information regarding our identity.
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- Schonpflug, U. “Theory and Research in Cultural Transmission: A Short History.” Cultural Transmission: Psychological, Developmental, Social, and Methodological Aspects, edited by Uta Schonpflug, Cambridge University Press, 2008, p. 9-30.
- “What is Intangible Cultural Heritage?” United Nations Educational, Scientific, and Cultural Organization, 28 Feb. 2020, https://ich.unesco.org/en/what-is-intangible-heritage-00003.
Is DNA my Book of Life?
Where do I come from? To many, the answer is based upon what we perceive of our biological roots. The ancestry testing industry has now empowered the general public to analyze their own genetic material. More than 26 million genetic ancestry tests were sold in 2018 and public interest in genetic ancestry tests is still skyrocketing (Regalado, 2020). If a person took all three types of genetic ancestry tests, including mitochondrial, Y-chromosomal, and autosomal testing, the results would yield an individual’s haplogroup and an ethnicity estimate. However, genetic ancestry testing results are limited and should not serve as a means for a complete understanding of one’s heritage.
There are generally three types of ancestry testing: mitochondrial DNA (mtDNA), Y-chromosomal (Y-DNA), and autosomal (atDNA) testing. mtDNA testing examines the test taker’s maternal line by analyzing the hypervariable regions of the maternally inherited mtDNA genome (Bettinger, 2019). Unlike other DNA, mtDNA does not undergo recombination which allows the genome to stay similar for long periods of time, making it possible to trace the maternal line back thousands of years. Similarly, Y-DNA testing examines the same characteristics, but of the paternal line. Y-DNA tests analyze short tandem repeats (Y-STR) or single nucleotide polymorphism (Y-SNP) in the paternally inherited Y-chromosome (Bettinger, 2019). In both tests, the test taker’s haplogroup is determined, which identifies individuals who share a common ancestor. The third type of test, which is also the most popular, is autosomal testing. “Autosomal” refers to the 22 pairs of chromosomes excluding sex chromosomes and mtDNA. Rather than only connecting customers to their matrilineal or patrilineal lines, autosomal testing allows for a full investigation of all genealogical lines. Commercial at DNA tests are conducted using genotyping, which investigates more than half a million selective locations called SNPs within the testing sample that are more prone to mutations (Bettinger, 2019). Because people from the same parts of the world tend to share the same mutations in their DNA that are often unique to their geological region, testing companies are able to trace an individual’s DNA mutations to estimate their ethnic background. However, the validity of DNA ancestry has been challenged on several grounds such as technological uncertainty and inconsistent reference population databases between different companies (Blell and Hunter, 2019). Genotyping is highly accurate but not exact. When processing as many as 1 million markers in a genomic sample, it is possible to have up to 1,000 errors (Resnick, 2019). Therefore, inconsistent results from identical twins have been reported (Huml et al., 2020). Furthermore, there is no clear-cut connection between one’s DNA and an ethnic group. Worldwide distribution of the human genome is weakly correlated with racial and ethnic categories because both are partially correlated with geography (Weiss and Fullerton, 2005).
The rise of genetic genealogy is quickly transforming how people are interpreting their identity and heritage. For example, a study reported that genetic testing results caused 40% of its participants to change the way in which they identify their ethnicity (Roth and Lyon, 2018). It is imperative to realize that ancestry testing results differ from the essence that cultural heritage supplies. Culture heritage is interpreted as an expression of the ways of living developed by a community and passed on from generation to generation. It is a legacy from the past: an irreplaceable source of inspiration and creativity (Franchi). Thus, cultural heritage implies a shared bond to the past, one shared among a living and growing community, whereas genetic ancestry is a fixed trait. DNA ancestry is limited: they can tell you how much of your DNA is inherited from your ancestors, but they are not able to convey the history of how our ancestors lived. In shaping one’s identity and group membership, social relationship and life experience are as important as genetic links.
Genetic ancestry tests allow people to explore beyond their own lifetime experiences, supplying them with scientific evidence that connects them to the people of the past. This can be a valuable asset as long as we bear in mind their limitations. Thus, DNA should not be the book of life that defines our heritage. Instead, today’s genetic ancestry data can be utilized as a contribution to future generations, broadening our knowledge in genealogy and improving genomic medicine for the well-being of all those who follow us in the years to come.
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Direct-to-consumer ancestry testing is an efficient and affordable way of learning the extraordinary story of one’s genetic roots. Using DNA extracted from a buccal swab, it algorithmically surveys up to 700,000 single-nucleotide polymorphisms (SNPs)––base-pair substitutions present in more than 1% of the population––and short tandem repeats (STRs)––stretches of highly mutable, repetitive DNA––for similarities to known population variants(1).
The three available ancestry tests can verify descent from a paternal or maternal lineage, map out migration patterns, or deconstruct one’s ethnic mix. They can affirm, but often contradict, one’s cultural identity.
Y Chromosome Testing
The Y chromosome offers geneticists a treasure trove of patrilineal data owing to its one-of-a-kind inheritance pattern. Since 95% of the Y chromosome does not recombine with the X, the number of motif repetitions within a father’s Y-STRs––collectively, his “haplotype” ––is passed nearly identically to his son, then to his son’s sons, and so on(2). Thus, Y-STRs act as genetic barcodes identifying a single male line of descent. Up to 111 Y-STRs from two individuals can be compared to determine their patrilineal relatedness as far back as 20 generations(3).
By contrast, SNPs occur one billion times less frequently than the polymerase slips that change STR length. They define broader “haplogroups,”: combinations of haplotypes sharing an SNP. Descendants of the 200,000-year-old “Y-chromosomal Adam,” the most recent common ancestor (MRCA) of all males, developed new SNPs as they left Africa that laid the basis for modern haplogroups corresponding to geographic regions. For example, members of Haplogroup L, defined by SNPs M11 and M20 among others, likely originate from India or Afghanistan(4).
Mitochondrial DNA (mtDNA) Testing
mtDNA is maternally inherited and does not undergo recombination. The 16.5 kb mtDNA genome evolves 5-10 times faster than nuclear DNA and is divided into one coding region and two polymorphic control/hypervariable regions: HVR1 and HVR2.
Though once the gold standard, HVR1 testing is currently the lowest resolution mtDNA test available. Even if two candidates’ HVR1 sequences match perfectly, shared maternal ancestry in the last 52 generations can only be confirmed with 50% certainty. Luckily, complete mtDNA tests, now becoming more affordable, can narrow the estimate to the genealogical time frame if a perfect match is found, guaranteeing shared maternal ancestry with 50% certainty in the last 5 generations(5).
In the last 150,000 years, more than 4000 mtDNA SNP haplogroups have descended from “Mitochondrial Eve,” the matrilineal MRCA of all humans(6). This enables both men and women to trace either their maternal line of descent with a phylogenetic tree or their maternal ancestors’ migration patterns with a map of haplogroups and their corresponding geographic locations over time.
Autosomal DNA (atDNA) Testing
Each parent passes down 22 recombined autosomal chromosomes to offspring, in sharp contrast with the unchanging, uniparental inheritance of Y-DNA and mtDNA. As a result, the newest generation contains about 50% of the SNPs from its parents, 25% of those from its grandparents, 12.5% of those from its great-grandparents, and so on. In this way, an individual’s atDNA acts as a dynamic record of genetic admixture: the combinations of ancestral lineages from sometimes distant populations.
An atDNA test can efficiently “reverse” the timeline of genetic admixture by scanning for ancestry informative markers (AIMs): SNPs known to be present at significantly higher frequencies in certain populations. AIMs integrate paternal and maternal lineages to offer the most holistic map of one’s modern ethnic mix and biogeographical origins.
However, this coverage comes at a cost. Since old atDNA is diluted and potentially lost with each successive generation, the test can only reliably relate specific individuals up to fifth cousins, necessitating a test of a parent or uncle to further extend the known family tree(7).
Ultimately, ancestry runs deeper than the strings of nucleotides within us. It is equally determined by the intangible: our traditions, beliefs, and ways of thinking. Indeed, our genetic results may strengthen a deep connection we’ve always felt to a culture or region. Consider, for example, the African Americans using DNA testing to re-unite with their ancestral tribes after their 19th-century forebears were displaced by slavery.
At the same time, however, our test results can alienate us.
Take, for example, an adoptee using an atDNA test to find his biological kin. What happens if he discovers a half-sister unaware of her father’s earlier relationships? What if he learns that his birth parents have passed, or that they don’t want to meet him?
Dividing as much as it demystifies: such is the quandary of the ancestry test.
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- Westen, Antoinette A., et al. “Analysis of 36 Y-STR Marker Units Including a Concordance Study among 2085 Dutch Males.” Forensic Science International: Genetics, Elsevier, 23 Oct. 2014, www.sciencedirect.com/science/article/pii/S1872497314002282.
- Mendez, Fernando L, et al. “An African American Paternal Lineage Adds an Extremely Ancient Root to the Human Y Chromosome Phylogenetic Tree.” American Journal of Human Genetics, Elsevier, 7 Mar. 2013, www.ncbi.nlm.nih.gov/pubmed/23453668.
- Ellen, and Hinkley. “What Is a Mitochondrial DNA Test?” DNA Testing Choice, dnatestingchoice.com/en-us/news/what-is-a-mitochondrial-dna-test.
- Veronese, Nicola, et al. “Mitochondrial Genetic Haplogroups and Cardiovascular Diseases: Data from the Osteoarthritis Initiative.” PLOS ONE, Public Library of Science, journals.plos.org/plosone/article?id=10.1371/journal.pone.0213656.
- Buckleton, J.S., et al. “The Interpretation of Lineage Markers in Forensic DNA Testing.” Forensic Science International: Genetics, Elsevier, 11 Mar. 2011, www.sciencedirect.com/science/article/abs/pii/S1872497311000329.
Nature Versus Nurture: Reflections on Genetic Ancestry and Cultural Heritage
Genetic ancestry testing has evolved from looking for short DNA repeat segments to using automated microarray technology to detect single nucleotide polymorphisms (SNPs) within genes. Whereas genetic ancestry testing has become a popular way of tracking people’s origins, it does not replace cultural heritage in defining our individuality.
The initial interest in genetic ancestry testing stemmed from research to solve genealogic brick walls and therefore first focused on decoding the Y chromosome and mitochondrial DNA. Being passed virtually unchanged from father to son, the Y chromosome represents a great way to understand paternal ancestry and allows people to trace back their geographical origins and family names (Kirkpatrick, 2017). Additionally, health research focusing on the Y chromosome has identified genetic haplotypes that have been linked to various male predominant health risks such as coronary artery disease (Charchar, 2012). Mitochondrial DNA testing on the other hand allows people to trace back their maternal ancestry. Indeed these energy producing organelles are solely inherited from one’s mother since spermatozoal mitochondria are destroyed upon fusing with the ovum. Mitochondrial circular DNA does not undergo recombination and therefore can be readily traced back to predecessors. Finally, the hypervariable regions in mitochondrial DNA have a faster mutation rate than nuclear DNA and are therefore more likely to differ from one individual to another (Kivisild, 2015). Overall, Y chromosome testing can track paternal ancestry and provide information on health risks whereas mitochondrial DNA testing sheds light on remote genetic origins and maternal lines.
With modern microarray technology, genetic testing of the entire human genome has become possible and has been commercialized for direct consumer ordering. In 2019, 26 million people have already completed at home genetic ancestry testing (Regalado, 2019). By examining SNPs across all 23 chromosomes, autosomal testing generates detailed relationship identification, linking people to unknown relatives who agreed to contribute their DNA data to the company’s database (Kirpatrick, 2017). Recently, these reports have included a wellness section, providing answers to the presence or absence of specific traits or genes linked to certain medical conditions (Smart, 2017). Lastly, autosomal DNA testing provides information on ethnicity and estimation of biogeographical origin in more detail than Y chromosome and mitochondrial testing (Kirpatrick, 2017). In fact, companies advertise their service claiming that by knowing the geographical origins of their ancestors, people will finally be able to find themselves and rediscover their cultural heritage. Are they mistaken?
Cultural heritage are the customs shared and experienced within a group of people that are passed on from generation to generation. Cultural heritage represents the traditions people have grown up with: the food they eat, the holidays they celebrate, the language they speak. How can this possibly be connected to genetic ancestry? One could argue that cultural heritage and genetic ancestry share common features. Both are passed on from parents to their offspring. Both may undergo change over the years. Genetic mutations are selected under pressures of the environment whereas cultural heritage evolves in an effort to integrate and adapt to new places and societies. People strongly identify with both their genetic ancestry and their cultural heritage. Both shape the way they view themselves and how they function within societal constructs
(Zhang, 2018). Twin studies have shown that monozygotic twins are more likely to share similar human values than dizygotic twins indicating that genes impact human values and therefore cultural heritage (Twito, 2020). Both cultural heritage and genetic ancestry impact health and disease: genetics does it through biology, whereas cultural heritage does it through exposures and habits.
Genetic ancestry is however vastly different from cultural heritage. Genetic code, unlike cultural heritage, is passed on from parents following meiosis. This calculated event is crucial for survival and contrasts with cultural heritage, which is generally loosely carried on and is likely to evolve rapidly as societies intermix. Furthermore, human genes cannot be edited at will despite today’s technology, whereas cultural heritage can be sought, immersed in, and adopted. Genetics are not learned whereas culture is, and can be acquired fluidly. Generations transition from one ethnic or racial identity to another as people relocate or intermarry. When it comes to health, cultural heritage can be modified to promote healthy behaviors whereas health risks linked to specific genes cannot be readily changed.
Nature designed our genetic DNA code, whereas our cultural heritage has mostly been nurtured and shaped by relationships and interactions. Both contribute to our individuality and make each of us unique. Both should be celebrated.
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- Twito, Louise, and Ariel Knafo-Noam. “Beyond culture and the family: Evidence from twin studies on the genetic and environmental contribution to values.” Neuroscience & Biobehavioral Reviews (2020).
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Studies of genetics have led to the development of ancestry testing, a patient-directed form of genetic testing that enables people to discover information about their own genomes and can reveal ancestors and ethnicity. At times, the new information may contrast with one’s identity or culture. However, ancestry testing provides people with important information about their ethnicity, paternity and maternity, and health risks determined by their ancestry(1). The three main types of ancestry testing are Y chromosome testing, which provides information about paternal lineage(2), mitochondrial DNA testing, which illuminates maternal lineage(3), and autosomal DNA testing that provides information about ancestry and relatives by analyzing the presence of SNPs in genomes.
Only males possess Y chromosomes, meaning that the genetic information on the Y chromosome can pass virtually unchanged from father to son. Thus, Y chromosome testing can provide information on the paternity of males, and their ancestors. Genetic information is derived by analysis of SNPs, or single nucleotide polymorphisms, and STRs, or short tandem repeats. SNPs are changes of a single nucleotide (point mutation) in a person’s DNA, and are an important marker of genetic variation within a population(4). STRs are DNA sequences of up to 100 base pairs in length, including a 1-6 base pair repetitive unit(5). The lengths and locations of STRs and SNPs on a Y chromosome can be compared to those from other Y chromosomes in the laboratory database(1).
The only part of the sperm to enter the head is the nucleus, thus the inheritance of cytoplasm, organelles, and the genes in the organelles is from the mother. Because of this, the mitochondria, and therefore mitochondrial DNA is inherited maternally. Mitochondrial DNA testing can provide information on maternal lineage and ancestors, similarly to the paternal information discovered through Y chromosome testing. The entire mitochondrial genome or two hypervariable regions can be sequenced. By comparing the sequences to the Cambridge Reference Sequence, information about maternal ancestry is discovered(1).
Autosomal chromosomes are the 22 non-sex chromosomes in humans. The testing of autosomal DNA involves the analysis of chromosomes 1-22, similar to the method of Y chromosome testing. In both methods, observation and comparison of SNPs are used. In autosomal DNA testing, the genotype at 700,000 SNPs is compared to both those of other individuals in the database and to the established patterns of ethnicities(1). Autosomal DNA testing provides more information about ethnic ancestry than mitochondrial DNA and Y chromosome testing but less about identification of individual ancestors.
There are many benefits of direct to consumer genetic testing: risk information for genetic disorders, carrier status for genetic disorders, information about paternity and maternity, and information about ancestry and ethnicity(1). Part of the appeal of genetic testing is the possibility of finding out something surprising about one’s heritage. However, sometimes the surprise is unpleasant – a feeling of loss of important cultural identity, or the knowledge of a different biological father. For instance, suppose there is an Eastern European family that follows traditions such as making pierogi, painting Easter eggs, and speaking the language of their home country. However, genetic testing could reveal that a member of the family actually has a low percentage of Eastern European ancestry. In this way, genetic ancestry information can contrast with what a person feels to be their identity, or the culture they have participated in their entire life. It is important for people who engage in genetic testing to realize that one’s culture does not derive from one’s DNA, nor are certain genes a requirement for participation in traditions.
Despite the potential to reveal upsetting information, there are many valid reasons to pursue ancestry testing, such as to discover the presence of genetic disorders, find relatives, and learn about one’s genome.
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- Euhus, D., Haley, B.B., Leitch, M., Rahimi A., Rao, M., Rao, R., Rivers, A., & Wooldridge, R. (2016). Genetic Ancestry using Mitochondrial DNA in patients with Triple‐negative breast cancer (GAMiT study). Cancer, 123(1), 107-113. https://doi.org/10.1002/cncr.30267
- (February 11, 2020). What are single nucleotide polymorphisms (SNPs)?. Retrieved from https://ghr.nlm.nih.gov/primer/genomicresearch/snp
- Fan, H., & Chu, J. Y. (2007). A brief review of short tandem repeat mutation. Genomics, proteomics & bioinformatics, 5(1), 7–14. https://doi.org/10.1016/S1672-0229(07)60009-6
Genetic ancestry companies are facing an emerging responsibility in the face of new consumer concerns about the relationship between ancestry and identity. With genetic technology rapidly improving in precision, speed, and cost-effectiveness, DNA testing companies’ next concern is with shifting their focus to fears that genetic ancestry information is potentially harmful to individual identity and privacy. All three of the main types of DNA testing available are affected by these concerns.
Y chromosome testing reveals direct male ancestry (1,2) since, apart from generational genetic mutations, this uniquely male sex chromosome remains relatively unchanged. Observing the Y chromosome (Y-DNA) at specific loci is therefore effective in confirming male genealogical relationships and discovering paternal haplogroups (1,4). Furthermore, observing mutations in the Y-DNA of male ancestors reveal potential health risks for individual men.
Mitochondrial DNA (mtDNA) testing, by contrast, is effective in tracking matrilineal ancestry and maternal haplogroups (1,2). In addition to demonstrating maternal ancestry, mtDNA sequencing suggests the potential risks of mitochondrial disorders caused by mutations. In these ways, mtDNA informs both identity and health.
Sequencing of DNA samples in autosomal DNA testing and observing genetic similarities or patterns between two individuals, families, or populations confirms ethnicity percentages, close relationships, and potentially inheritable conditions (7). In general, autosomal DNA testing is quite precise, though as with the previous two methods, the accuracy of the result depends on the size of the ancestry testing company’s DNA database.
Genetic ancestry information and cultural heritage are both important vectors of family history. On the one hand, the food we eat, the religion we believe in, and the family traditions we have are heavily influenced by cultural heritage. On the other hand, genetic ancestry information provides us with invaluable knowledge of our predecessors and the historical ties they reveal. For instance, tracing human Y-chromosome haplogroups can identify ancient population movements (4), allowing us to glimpse even our remotest origins.
When societal constructs of race make individuals closely associate their identity with their ethnic background, DNA testing can hold power over an individual’s identity, potentially defining who they are in limiting ways (5). This potentially dangerous power is the source of rising consumer dissent in the face of increased testing availability. When major DNA testing companies like 23andMe advertise their products as providing an introduction to the buyer’s true self, they distort the complexities of identity in a multiethnic society. Assimilating identity to DNA risks promoting narrow, even racist, attitudes (3).
Despite the many uses of DNA testing, our DNA can’t directly influence the factors that determine our cultural heritage and, ultimately, identity. Genetic technologies have improved significantly over the past few decades, but there is still work to be done. With data inaccuracies and suspicions of bi-parental mitochondrial inheritance, the world needs to accept that DNA testing is far from perfect and, even in its ideal state, doesn’t hold the key to discovering one’s identity (6). While the issue customers have with inaccuracies, privacy, and even cost will likely be resolved in coming decades with the progression of genetic technologies, larger questions about the use of DNA testing will remain. It is incumbent on companies that offer such testing to be more careful in advertising their products to customers, resisting sensational exaggerations. DNA is a language that can be used to communicate ancestry, important historical facts, and prevent malignant conditions. In the larger human conversation, however, it is only one voice.
- Genetic Genealogy, web.stanford.edu/~philr/Bachman/DNABachman3.html.
- AncestrySupport, support.ancestry.com/s/article/Y-DNA-mtDNA-and-Autosomal-DNA-Tests
- Freedman, Aaron. “Perspective | Can DNA Tests Tell Us Who We Are? Only If We’re Racists.” The Washington Post, WP Company, 5 Feb. 2020, www.washingtonpost.com/outlook/can-dna-tests-tell-us-who-we-are-only-if-were-racists/2020/02/05/7adbdcfe-3e12-11ea-baca-eb7ace0a3455_story.html.
- Grugni, Viola, et al. “Analysis of the Human Y-Chromosome Haplogroup Q Characterizes Ancient Population Movements in Eurasia and the Americas.” BMC Biology, BioMed Central, 24 Jan. 2019, www.ncbi.nlm.nih.gov/pubmed/30674303.
- Lawton, Georgina. “’It Made Me Question My Ancestry’: Does DNA Home Testing Really Understand Race?” The Guardian, Guardian News and Media, 11 Aug. 2018, www.theguardian.com/lifeandstyle/2018/aug/11/question-ancestry-does-dna-testing-really-understand-race.
- Luo, Shiyu, et al. “Biparental Inheritance of Mitochondrial DNA in Humans.” PNAS, National Academy of Sciences, 18 Dec. 2018, www.pnas.org/content/115/51/13039.
- “What Is Genetic Ancestry Testing? – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, ghr.nlm.nih.gov/primer/dtcgenetictesting/ancestrytesting.
“Haplogroups Explained.” 23andMe Blog, 23andMe, 17 Dec. 2019, blog.23andme.com/ancestry/haplogroups-explained/.
“Haplotype.” Genome.gov, www.genome.gov/genetics-glossary/haplotype.
Molla, Rani. “Genetic Testing Is an Inexact Science with Real Consequences.” Vox, Vox, 13 Dec. 2019, www.vox.com/recode/2019/12/13/20978024/genetic-testing-dna-consequences-23andme-ancestry.
The development of direct-to-consumer ancestry testing has provided a substantial group of customers with comprehensive information about their genealogy. Over the years, as the technology has become more refined, the accuracy and accessibility of this testing has greatly improved. Moreover, the three main types of ancestry testing—Y chromosome testing, mitochondrial DNA testing, and autosomal DNA testing—each express different aspects of the ancestral information of an individual. This subsequent wealth of information may even allow people to regain or develop a newfound appreciation for their cultural heritage. Although there is a distinction between a person’s genetic identity and their cultural identity, taking a combination of the three aforementioned ancestry tests can provide an opportunity for a profound introspection into the relation between one’s ancestry and their traditions.
Y chromosome testing is unique in that it reveals the history of the father’s side of the family. Because females lack the Y chromosome, this is a test that can only be taken by males. However, women seeking to learn about their paternal history can recruit a close relative to take this test for them. The person taking the test would send a saliva sample to the lab which conducts the Y-DNA test. The lab would then isolate the DNA from the saliva and begin analysis.
Y-DNA testing is done by examining short tandem repeats (STR) and single nucleotide polymorphisms (SNP) of the tester’s DNA. These STR and SNP sections can act as genetic markers because they vary from person to person, creating different alleles. These results can then be compared to the results of another individual in the database or test group, in order to identify a possible relationship. The presence of mutations in the DNA segments can also be used to identify a timeframe in which the person taking their test and their genetic relative shared a common male ancestor. Thus, someone who takes a Y chromosome test would gain a deep
insight into their patrilineal ancestry (3).
Mitochondrial DNA (mtDNA) testing differs from Y chromosome ancestry testing because it reveals the information about the mother’s lineage, rather than the father’s. This is because mtDNA is transferred from a mother to her children without modification. Current mtDNA analysis techniques involve sequencing the two highly variable sections of the DNA: HVR1 (16024-16569) and HVR2 (00001-00576). A perfect match between two people who took the mtDNA test would mean that they share a common female ancestor (1).
Autosomal DNA (atDNA) testing contrasts the other two methods because it surveys chromosomes 1-22 and X. It is also the type of test that is used by many of the largest genetic genealogy firms to estimate ethnicity. This test may inspect up to 700,000 SNPs, and its results are compared with previously logged results in the company’s database. This helps contextualize the results and allows these corporations to correlate certain trends in the DNA to certain ethnicities. Autosomal DNA testing can also be used to locate and connect relatives. This is because DNA recombination causes a reduction the amount of inherited DNA from a single ancestor by about half each generation (5). Another tool that is often included in at DNA testing is X-chromosome sequencing and analysis. Because males can only inherit their X chromosome from their mother, ancestry companies can use X-chromosome testing to reduce the possibilities for ancestral lines (7).
In the modern age, the trio of DNA testing types has a weighty influence on culture and heritage. Initially, cultures may have originated when people of similar ethnicities developed common ways of living and experiencing daily life. During this time, genetic similarities would have been more strongly correlated with cultural expression (6). However, over time, many distinct cultural groups have formed within the same ethnicities worldwide. This is likely because culture is not static; rather it is alive and ever-changing. As families change through the generations, they adopt new traditions and customs (4). One’s predetermined genetic information cannot necessarily account for this cultural evolution. While general cultural trends may still be present among genetically similar people, on a local level, culture is much more nuanced. However, this fact does not discount the ability of genetic testing services to bring families together and develop new cultures. Current ancestry testing has allowed people to rediscover their familial origins which may even help them find long-lost relatives, helping foster the development of new family traditions (2). This is a comforting notion in an ever-changing world.
1. Amorim, António et al. “Mitochondrial DNA in human identification: a review.” PeerJ vol. 7 e7314. 13 Aug. 2019, doi:10.7717/peerj.7314
2. Curtis, Caitlin. “How DNA Ancestry Testing Can Change Our Ideas of Who We Are.” The Conversation, 20 Jan. 2020, theconversation.com/how-dna-ancestry-testing-canchange-our-ideas-of-who-we-are-114428.
3. Jobling, M A et al. “The Y chromosome in forensic analysis and paternity testing.” International journal of legal medicine vol. 110,3 (1997): 118-24. doi:10.1007/
4. “Letters: ‘My Culture Was in My DNA’.” The Atlantic, Atlantic Media Company, 9 Oct. 2018, www.theatlantic.com/letters/archive/2018/10/letters-does-your-ancestrydetermine-your-culture/572305/.
5. Royal, Charmaine D et al. “Inferring genetic ancestry: opportunities, challenges, and implications.” American journal of human genetics vol. 86,5 (2010): 661-73.
6. Via, M et al. “Recent advances of genetic ancestry testing in biomedical research and direct to consumer testing.” Clinical genetics vol. 76,3 (2009): 225-35. doi:10.1111/j.1399-0004.2009.01263.x
7. Wang, Jian et al. “X-chromosome genetic association test accounting for X-inactivation, skewed X-inactivation, and escape from X-inactivation.” Genetic epidemiology vol. 38,6 (2014): 483-93. doi:10.1002/gepi.21814
Ancestry is an essential component of human identity. Familial ties and knowledge of one’s roots have been an integral part of human civilization for centuries. As ancestry testing becomes more affordable, more people have access to the genetic information obtained through mitochondrial, Y-chromosome, and autosomal DNA testing. An individual who underwent all three ancestry tests could trace their direct maternal and paternal lines, track the migrations of their prehistoric ancestors, and obtain percentages of their ethnic makeup (7). Sometimes this information contrasts with one’s conception of his/her cultural heritage, reigniting the age-old question: is biology or culture truly more important in determining human identity?
The unique nature of mitochondrial DNA (mtDNA) allows geneticists to trace a client’s direct maternal line. mtDNA is found in the cell’s mitochondria and resembles circular bacterial chromosomes, supporting the endosymbiont hypothesis that mitochondria were originally prokaryotes that survived endocytosis by early eukaryotes (6). Furthermore, mtDNA replication is regulated by genomic imprinting: the process by which methyl groups are attached to DNA, silencing either the maternal or paternal allele of a gene in early development (6). In the case of mtDNA, these methylation patterns silence the paternal mtDNA. Therefore, only females pass mtDNA to their children (6). Comparative analysis of mtDNA can thus be used to track one’s matrilineal ancestry and identify living relatives with similar mtDNA sequences (6).
Just as mtDNA testing tracks matrilineal ancestry, Y chromosome testing traces the direct paternal line. The Y chromosome is one of the two human sex chromosomes and is only inherited by males (3). Y chromosome testing is used to track patrilineal ancestry and identify living male relatives by analyzing the frequency of single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs) in the DNA (3). STRs are groups of repeating nucleotides that vary greatly among individuals, whereas SNPs are variations in individual DNA nucleotides (5,8). Matching STRs among men signifies a close genetic relationship, and the number of matching SNPs indicates how closely related the two individuals are (5,8).
mtDNA and Y chromosome testing also reveals an individual’s maternal and paternal haplogroup: genetic populations characterized by variation in mtDNA and Y chromosomes that arose from genetic mutations in ancient humans (3, 6). Each haplogroup is associated with a prehistoric migration, allowing individuals to track the ancient paths of their ancestors. Due to the low incidence of Y chromosome and mtDNA mutation, Y chromosome and mtDNA testing can trace one’s paternal and maternal lines back 60,000 and 150,000 years to “Y Adam” and “Mitochondrial Eve,” the most recent common male and female ancestors of all humans (3,6).
Autosomal DNA testing is the broadest form of ancestry testing. Each human inherits twenty-two autosomes, or non-sex chromosomes, from each parent (7). This allows individuals to identify living and deceased relatives on both sides of their family tree. Like Y chromosome testing, autosomal testing compares the client DNA’s STRs and SNPs to other DNA samples within a database to determine relatedness (5,8). Autosomal testing also provides percentage estimates of the client’s ethnic heritage by comparing his/her DNA to a “reference panel” of DNA samples associated with specific world regions (7).
In many cases, ancestry testing results are cause for celebration. For some, ancestry testing can provide cultural epiphanies by revealing connections to peoples and traditions previously unknown. This is especially true for members of historically displaced groups such as Amerindians and African Americans, who were forced from their homes and pressured to culturally assimilate (4). For example, an individual’s Native American ancestors may have been forcibly sent to boarding schools where indigenous languages and customs were forbidden. DNA ancestry testing could reacquaint this individual with a lost aspect of his/her native heritage (4).
However, ancestry testing results may also conflict with an individual’s cultural heritage, provoking crises of identity. Increasing numbers of “false paternity” cases have been documented, where ancestry testing revealed that clients’ father figures were not their biological parents (7). Testing should not be taken lightly, for such revelations can complicate questions of identity. For example, in historically colonized societies such as Latin America, ancestry testing may reveal mixed ethnic heritage contradicting the client’s family customs (2). A Mexican client raised with strong indigenous influences may discover that they have European ancestry (1).
Ancestry testing can reveal unexpected genetic secrets, and it can also open the door to a more complete understanding of human identity. The power of genetic testing is that it links humanity, showing that we are related across time and enriched by diverse cultural traditions.
- Chacón-Duque, Juan-Camilo, Kaustubh Adhikari, Macarena Fuentes-Guajardo, Javier Mendoza-Revilla, Victor Acuña-Alonzo, Rodrigo Barquera, Mirsha Quinto-Sánchez, et al. “Latin Americans Show Wide-Spread Converso Ancestry and Imprint of Local Native Ancestry on Physical Appearance.” Nature communications. Nature Publishing Group UK, December 19, 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6300600/.
- Kaiser, Jocelyn. “When DNA and Culture Clash.” Science. American Association for the Advancement of Science, December 9, 2016. https://science.sciencemag.org/content/354/6317/1217.
- Kivisild, Toomas. “The Study of Human Y Chromosome Variation through Ancient DNA.” Human genetics. Springer Berlin Heidelberg, May 2017. https://www.ncbi.nlm.nih.gov/pubmed/28260210.
- “Native Nations Face the Loss of Land and Traditions (U.S. National Park Service).” National Parks Service. U.S. Department of the Interior, August 14, 2017. https://www.nps.gov/articles/negotiating-identity.htm.
- Romsos, Erica L, and Peter M Vallone. “Rapid PCR of STR Markers: Applications to Human Identification.” Forensic science international. Genetics. U.S. National Library of Medicine, September 2015. https://www.ncbi.nlm.nih.gov/pubmed/25937291.
- Rothhammer, Francisco, Lars Fehren-Schmitz, Giannina Puddu, and José Capriles. “Mitochondrial DNA Haplogroup Variation of Contemporary Mixed South Americans Reveals Prehistoric Displacements Linked to Archaeologically-Derived Culture History.” American journal of human biology : the official journal of the Human Biology Council. U.S. National Library of Medicine, November 2017. https://www.ncbi.nlm.nih.gov/pubmed/28653803.
- Royal, Charmaine D, John Novembre, Stephanie M Fullerton, David B Goldstein, Jeffrey C Long, Michael J Bamshad, and Andrew G Clark. “Inferring Genetic Ancestry: Opportunities, Challenges, and Implications.” American journal of human genetics. Elsevier, May 14, 2010. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2869013.
- Shastry, Barkur S. “SNPs: Impact on Gene Function and Phenotype.” Methods in molecular biology (Clifton, N.J.). U.S. National Library of Medicine, 2009. https://www.ncbi.nlm.nih.gov/pubmed/19768584.
When living in an age of extreme consumerism nearly everything, including a person’s ancestral history and genetic makeup, has been made easily accessible to the customer. The field of genomics and genetics has long been useful in identifying genes that code for specific traits as well as studying inherited autosomal disorders such as cystic fibrosis or sickle cell anemia by looking at gene mutations. However, genetic information is not only being used to identify and detect disorders, but also to learn more about a person’s ancestral history, their race, and ethnic makeup. Often, three types of ancestry tests are used: Y chromosome, mitochondrial DNA, and autosomal DNA testing. While each of these tests provides different information for the consumer, they all report genetic ancestry. Yet, this often does not hint toward cultural heritage, which can vary vastly from a person’s biological programing.
As opposed to mitochondrial DNA testing and autosomal DNA testing, Y chromosome testing involves only patrilineal ancestry. Since males have XY chromosome pairs, as opposed to female’s XX, this test can trace a males paternal haplogroup, or ancient group of patrilineal descent (Poznik, 2016). This is possible because throughout generations, the Y chromosome does not undergo recombination and remains relatively unchanged. This allows for members of different families with the same surname to see if they came from a common ancestor and are therefore related. This distinction is made through markers, or spots on the Y chromosome, that are unique to different ancestral groups (“The Y Chromosome”). Not only can this be useful for learning about distant relatives, but it can help adopted children find their fathers or other male members of their family.
As opposed to Y-chromosome testing that reveals a male’s patrilineal descent, mitochondrial ancestry testing reveals a person’s matrilineal descent. Similar to Y chromosomes, mitochondria are nearly identical between generations of women and can therefore reveal a person’s maternal haplogroup (Farmer, 2018). However, unlike Y chromosomes, males and females both have mitochondria and can therefore take this test. Even though most DNA is located in a person’s chromosomes, a small amount is contained in the mitochondria. This can be especially useful for identifying maternal relatives since unlike men, women typically change their surname upon marriage. Moreover, mitochondrial DNA is circular and contains only 37 genes as opposed to the 30,000 genes in the rest of DNA. This makes it easier to identify similar genes and markings that are looked for during Y chromosome testing (Hinkley, 2016).
The third option for ancestral DNA testing is through autosomal DNA. This technique provides the consumer with the most information, since all 22 pairs are examined for regions, or markers, that are then compared with other family members. Depending on how closely one’s DNA matches another person’s, this can point to the type of relationship between them. Therefore, this makes autosomal DNA testing useful for recent ancestry and close relatives (Saloum de Neves Manta, 2013). It is also more helpful than the other options because it can establish exact relationships between people as opposed to the other two tests that can only identify how distant the relative is and on what side of the family they are on. Similar to mitochondrial DNA testing, anyone can do this and receive plentiful information about potential relatives and places of origin (Hinkley, 2016). Unlike the other two tests, however, autosomal DNA testing reports ancestry from both parents since approximately 50% of a person’s autosomes are from their mother and the other 50% the father (Kerry, 2016). Autosomal DNA can also tell a person their DNA heritage, or population group, as well as their ethnic profile.
While all three tests provide information about a person’s genetic ancestry, these results can often be misleading in terms of cultural heritage. For example, if a person takes an autosomal DNA test and finds out that they are 10% Polynesian, they might have never eaten Polynesian food or even seen a Polynesian person in their lives. A person’s traditions, customs, and way of dress will not necessarily be the same just because of a genetic relation. These factors are largely influenced by the environment, changing time periods, and altering social norms (Goldman, 2014). Additionally, since young children are easily shaped and their brains are more plastic, they will learn behaviors such as work ethic, and manners from their parents instead of their DNA. However, both DNA tests and cultural history are beneficial in deconstructing the past and the people in familial generations decades before you.
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Ellen, & Hinkley. (n.d.). What is a mitochondrial DNA test? Retrieved from https://dnatestingchoice.com/en-us/news/what-is-a-mitochondrial-dna-test
Goldman, J. G. (2014, April 10). How human culture influences our genetics. Retrieved from https://www.bbc.com/future/article/20140410-can-we-drive-our-own-evolution
McDermott, M. (2019, August 29). Y-DNA Test: What is a Y Chromosome Test and Which is Best. Retrieved from https://www.genealogyexplained.com/dna-testing/y-dna-test/
Poznik, G. D. (2016, January 01). Identifying Y-chromosome haplogroups in arbitrarily large samples of sequenced or genotyped men. Retrieved from https://www.biorxiv.org/content/10.1101/088716v1.abstract
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