When DNA ancestry tests reveal something surprising

“Hey, we’re half French,” was the text from my brother a couple of months ago, accompanying a screenshot of his Ancestry.com results. I found this message surprising for two reasons.

First, there has never been any mention of French ancestry in our family story. Our father is from Portugal, and his parents and their parents were also Portuguese, or so our story goes, and our mother is “melting-pot-American,” with likely roots in Ireland and England. Second, I was struck by the realization that my brother had gone and done this without ever mentioning it to me.

My first question back to him was “you do know what I do for a living, right?” Indeed, he was hazy on the details.

I have spent the last several years of my career exploring the integration of genomic information into people’s lives. My research generally focuses on the use of this technology in clinical care in different groups, including newborns and active duty military personnel, as opposed to more recreational uses like ancestry tests.

I mentioned this to him and posed my second question: “you realize you’ve shared about half of my genetic information with this company, too, right?” His answer made it clear to me that we’re just not used to thinking of genetic information as belonging to more than just the individual.

Or, at least we weren’t then. This was back in the beginning of April, right before the news of the arrest of the suspected Golden State Killer. And now we’re starting to see a lot more conversation about the shared familial nature of genetic information and the potential implications.

In fact, right after the story broke, I went back to my brother with the story and a new question: “did you see this?” “Yep,” he replied, “hope you haven’t done anything illegal.”

My brother’s seemingly innocuous and recreational activity brought a lot of issues related to my work into sharp relief for me, including issues of privacy, the accuracy of ancestry tests, and how people respond to genetic information, particularly unexpected genetic information.

But beyond the big questions I wrestle with in my work, it also has the very ordinary impact of making me question what I have always understood to be my family’s origin story.

So, what does this result of being half French mean for my family’s sense of identity? It depends on who you ask.

My father, having been born and raised in Portugal, questioned the accuracy of the results and summarily ignored them. My mother is convinced I would have more Portuguese ancestry show up if I were to do the test myself because my father and I look and act more alike, while my brother favors my mother’s side of the family. And my brother doubled down and decided to get both our parents tested, as well as sign up for the 23andMe test, too, so he can compare results.

And me? I take these genetic tests with a grain of salt. While the science behind sequencing is strong, (i.e., they can reliably figure out the order of your As, Cs, Gs, and Ts) the interpretation of that information to determine where your ancestors are from is more of an art and varies between companies.

And I’m still rooting for Portugal in the World Cup this year. C’est la vie!

-By Stacey Pereira, Ph.D., assistant professor in the Center for Medical Ethics and Health Policy at Baylor College of Medicine