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Genetic testing is an inexact science with real consequences

How flawed genetic testing could be used for more than screwing up your race.


Three years ago, I put my faith in a 23andMe DNA test and got burned.


While most of my results initially checked out — about 50 percent South Asian and what looked like a 50 percent hodgepodge of European — there was one glaring surprise. Where roughly 25 percent Italian was supposed to be, Middle Eastern stood in its place. The results shocked me.


Over the years, I had made a lot of the Italian portion of my heritage; I had learned the language, majored in Latin in college, and lived in Rome, Italy, for my semester abroad. Still, as a rational person, I believed the science. But my grandmother, whose parents moved from Sicily to Brooklyn, where she was born and grew up speaking Italian, refused to accept the findings.


Fast forward to this summer, when I got an email about new DNA relations on 23andMe and revisited my updated genetic results, only to find out that I am, in fact, about a quarter Italian (and generally southern European). But it was too late to tell my grandma. She’s dead now and I’m a liar.


This sort of thing happens a lot because ancestry DNA testing — and genetic testing in general — is an inexact science that’s prone to errors throughout almost every step of the process. As my Vox colleague Brian Resnick has explained, some small amount of error is unavoidable within the technical portion of analyzing your DNA.


Making the results of these tests even more unreliable is the fact that their whole ancestry component is based on self-reported surveys from people who say they belong to one ancestry or another — an inherently flawed practice. Sample sizes vary by location and by testing company, so there’s a big disparity in data quality, especially if you happen to not be white. That’s because Europeans are much more represented in DNA databases and therefore, much more exact information can be gleaned about their DNA.


Of course, what would be much more troubling than getting someone’s heritage or hair color wrong is using that information to inform decisions made about that person. And as more people submit their DNA to genetic testing companies, and more law enforcement and government agencies figure out ways to use this deeply personal genetic information, it could be used against us. Making matters more concerning is that there are very few legal safeguards on what companies and governments can and can’t do with data gleaned from direct-to-consumer genetic tests.


“Under existing law it would be legal to very broadly share consumer information if you disclose that that was happening in the privacy policy and terms of service with the customer,” James Hazel, a research fellow at Vanderbilt University Medical Center, who has done research on genetics test privacy policies, told Recode. And companies don’t have to stick with existing privacy policies, either. “Nearly every company reserves the right to change their privacy policies at any time.”


Of course, few people read privacy policies in the first place (under 10 percent always do so, according to a new Pew Research study). And the existing privacy policies for genetic testing aren’t necessarily clear or forthcoming. Hazel found that 39 percent of the 90 genetics testing companies he researched had “no readily accessible policy applicable to genetic data on their website.


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