Since 2012, more than 18 million people have mailed their spit-filled vials to [Ancestry DNA], which analyzes the genetic material for markers that indicate regional heritage and sends back reports on the geographic areas from which each customer’s ancestors hail, broken down into percentages. [A recent] revision to these estimates [that indicated many people have more Scottish heritage] elicited elation, panic—and no small amount of confusion.
An American woman blamed her Scottish ancestry for her loud mouth, while another man seemed more distressed by the news: “Help before I go out and buy a kilt!,” he tweeted @Ancestry.
Jokes, jokes, jokes. And yet, they reveal some popular misunderstandings about what these tests really mean. Of course, nobody actually became more Scottish. Ancestry’s scientists simply refined the company’s algorithm.
But the social media reactions suggest an erroneous belief, one that these companies’ marketing sometimes helps advance: that race and ethnicity are genetically determined, and that they tell you something about your essential nature.
“There is no Korean SNP or French SNP,” says Barry Starr, Ancestry’s director of scientific communications. “So it really comes down to probability: This particular SNP at this particular spot is a bit more common in France than it is in Korea. It’s the building up of all those small probabilities that gives you the strength to make a prediction.”