Researchers underscore limitations of genetic ancestry tests

Although many people rely on commercially available genetic tests for insights into their ancestry, consumers should be aware of significant limitations in such testing, according to a group of researchers commenting in today’s issue of the journal Science.

The authors include Pilar Ossorio, associate professor of law and bioethics; and Joan Fujimura, professor of sociology; both from the University of Wisconsin–Madison.

In "The Science and Business of Genetic Ancestry Testing," Fujimura and Ossorio and 12 other researchers from universities across the nation call upon the scientific community to better educate the public about the limitations of the tests, and urge consumers to approach the tests with caution. The first author of the article is Deborah Bolnick, assistant professor of anthropology at The University of Texas at Austin.

At least two-dozen companies market genetic ancestry tests, which typically cost between $100 and $900, to help consumers determine the origins of their ancestors. More than 460,000 people have purchased the tests during the past six years and public interest is growing.

The researchers argue that the assumptions and limitations of the tests make them less informative than many realize, and commercialization has led to misleading practices that reinforce misconceptions. Some of the tests’ limitations identified include:

• Most tests trace only a few of your ancestors and a small portion of your DNA;
• The tests cannot identify all of the groups or locations around the world where a test-taker’s relatives are found;
• Tests may report false negatives or false positives;
• Limited sample databases mean test results may be subject to misinterpretation;
• There is no clear-cut connection between DNA and racial/ethnic identity;
• Tests cannot determine exactly where ancestors lived or what ethnic identity they held.

Consumers often have deeply personal reasons for taking the tests. Some hope to validate genealogical records or fill in gaps in family histories. Others are searching for a connection to specific groups or places in Eurasia or Africa. Many African Americans hope the tests will help them trace ancestral links lost during the transatlantic slave trade. Other Americans have taken the tests in hope of obtaining Native American tribal affiliation or to challenge tribal membership decisions. However, an individual’s social or ethnic identity does not always match his or her genetic ancestry.

"Not all companies make clear the limitations and assumptions underlying these tests," said UT Austin’s Bolnick. "Because it is important for consumers to understand what the tests can and cannot tell them, we are encouraging professional genetic and anthropological associations to develop policy guidelines regarding genetic ancestry testing."