A Cautionary Tale: What DNA Testing Cannot Tell You
In 2007, the New York Times featured an article about Henry Louis Gates, Jr., director of the W.E.B. Du Bois Institute for African and African-American Research at Harvard University. Mr. Gates hosted a televised special on PBS called “African American Lives,” which explored the ancestry of several famous African-Americans through DNA testing. Mr. Gates and his televised program were instrumental in catapulting the use of scientific testing into mainstream circles. When the New York Times published the article, public interest in DNA testing had spawned the creation of approximately two dozen companies offering such services. This number has continued to grow as genealogy has become an increasingly popular hobby and the costs of testing have made this service accessible to many people.
However, the genealogical picture afforded by these tests is not always so clear. After discovering inconsistencies in his own personal testing, Mr. Gates expressed reservations about the claims made by such companies. In Mr. Gates’ case, two tests done by different companies five years apart produced drastically different results; the first concluded that his maternal ancestors could be traced back to Egypt, probably to the Nubian ethnic group, and the second test determined that his origins were not Nubian at all, but most likely European. According to Mr. Gates, the first company never reported that he had multiple matches, mostly originating from Europe. This finding demonstrates one of several contentious aspects of DNA testing: that is, its capacity to accurately determine the originating country or ethnic group of any one individual, particularly African-Americans and Native Americans.
In recent years, some scientists have cautioned users about the drawbacks of scientific testing as a tool for gathering genealogical information. They assert that limited information in these companies’ resource banks might lead customers to misinterpret data or draw erroneous conclusions. Testing companies evaluate a person’s genetic composition by comparing his or her DNA to a database of DNA samples from individuals currently living in a particular region. However, we know that our ancestors rarely stayed in one place. With their genetic data scattered about and outsiders randomly entering that geographic area, it would be difficult for geneticists to distinguish one region’s population from another as residents of one region would be unlikely to develop a single set of identifying genetic mutations. The inhabitants of any one region today are genetically distinct from the inhabitants of that area before migration. Thus, even if your DNA matches that of another person who currently lives in that country, town or tribe, this does not conclusively establish that your ancestors descended from that area.
This limitation is especially applicable for African-Americans whose lineage is scantly documented. Bert Ely, a geneticist who co-founded the African-American DNA Roots Project in 2000, was searching for a method to trace ancestry between African-Americans and ethnic groups in Africa. He compared the DNA sequences of 170 African-Americans against those of 3,725 people living in Africa. He found that most members of the test group had genetic matches to multiple ethnic groups in Africa. The multitude of genetic similarities rendered it impossible to match any one African-American with a single ethnic group. He similarly could not obtain conclusive data when using DNA to determine the country of origin for native Africans. The lesson according to Mr. Gates and Mr. Ely is this: while scientific testing certainly has a place in genealogical research, particularly for those who lack an abundant paper trail, users should not rely on it as definitive proof of their origination. Somewhere down the road, those findings may be challenged.
