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Saturday, November 17, 2007

What can I learn about my ancestors from my DNA?

What can I learn about my ancestors from my DNA? What companies provide this information? How much does it cost? What exactly do I learn?


  1. An excellent answer to this question has been provided by Bolnick et al., a group of 14 scientists writing on “The Science and Business of Genetic Ancestry Testing” for Science (Vol. 318, pp. 399-400). They are primarily social scientists, but they demonstrate mastery of the genetics involved.

    I encourage everyone interested in this question to read the original, but nevertheless provide some excerpts here.

    "mitochondrial DNA and Y-chromosome tests provide information about the maternal and paternal lines," respectively. These lines represent "only one ancestor each generation," and "no information about most of a test-taker's ancestors." "Genetic ancestry testing can identify some of the groups and locations around the world where a test-taker's haplotype or autosomal markers are found, but it is unlikely to identify all of them. They cannot pinpoint the place of origin or social affiliation of even one ancestor with exact certainty. Although wider sampling and technological advancements may help, many of the tests' problems will remain." The bottom line is that your DNA can only tell you where your ancestors are likely to have come from, not where they actually did come from.

  2. This question is addressed by an article in today's New York Times ("DNA Tests Find Branches but Few Roots"). The article is nice in that it compares the cost of ancestry testing by various companies, shows that results differ, and quotes Henry Louis Gates Jr. making reasoned assessments of the role that DNA testing can play.

    The Times reports that "Mr. Gates recently teamed up with Family Tree DNA, a DNA testing and genealogy firm in Houston, to provide genetic testing and genealogy work for African-Americans. The new venture is called AfricanDNA.

    "“What we hope to do is combine this with genealogical and other records to try to help people discover their roots,” he said. “The limitations of current genetic DNA tests mean you can’t rely on this alone to tell you anything. We hope to bring a little order to the field.”"

    The article fails to say which companies provide customers with the raw genotype information that they can use to make their own assessments as more information becomes publicly available.