How—and why—DNA Testing Uses Biased Reference Databases
Are DNA ancestry tests equally accurate for all test takers?
Because of the Eurocentric bias of genetic reference databases, DNA ancestry test results for individuals of African and Asian descent are often less detailed than results for individuals of European descent.
How—and why—DNA Testing Uses Biased Reference Databases
Published: January 27, 2021
Narrator: These 14 people are about to experience DNA ancestry testing for themselves.
Cherry Richardson: 'Cause there are so many kids I’m growing up with who are all in the same situation. We don’t know our heritage. We could probably safely assume that our ancestors’ ancestors had something to do with, like, slavery and things like that, but we don’t really know where we came from.
Narrator: Cherry Richardson is taking part in a research study, at West Chester University, in Pennsylvania.
Bessie Lawton: So, we have a research protocol by which we collect data for this particular project.
Narrator: The study is run by two communications professors, Bessie Lawton and Anita Foeman. The question they’re asking is, “How does DNA testing affect our understanding of who we are, and also, our ability to understand what makes us different?”
Lawton: And after we receive the results, we bring you together.
Anita Foeman: The whole idea is to listen to each other and talk with one another.
Narrator: Anita was inspired to start the project because of her experiences as a diversity trainer.
Foeman: I thought looking at our DNA was a really interesting way to approach this whole conversation about race and diversity, in a way that was not going to make people defensive. And that has happened.
Tyquine Golden: We don’t identify ourselves with Africa. We just say we’re Black. You know, we literally separated from that which we came from.
Narrator: In a previous test with Ancestry, Tyquine Golden was told his roots were 80 percent West African, and 20 percent British. In today’s test with FamilyTreeDNA he hopes to learn more.
Golden: They got everybody. My suspicions might lead me to say, somewhere in slavery, 20 percent might’ve came in and have been integrated with our DNA And that might not have been voluntary.
Tshaka Cunningham: I think, as an African American, it’s a tough thing to grapple with, when you think about the origin of your Caucasian, or white ancestry. That often happened due to rape and mistreatment, but it is part of your history. So you have to confront it on some level and understand it. It’s part of how you got here.
Golden: I don’t want to hide from the truth, no matter how bad it could be.
Narrator: Now it’s time to collect DNA…
Lawton: You can turn it around a little bit, to capture more.
Narrator: …and ship the samples off to Houston.
So, how do D.T.C.s like FamilyTreeDNA come up with a breakdown of your ancestry? It’s a process that also centers around SNPs, those places in our DNA that most frequently vary between people.
The company compares your SNPs with those of people in what are called “reference groups,” people alive today whose DNA has been tested and who share patterns of SNPs that scientists have found to be typical for the region in which they live. Those patterns are compiled into a database.
But how well does it represent test takers?
Foeman: They’re telling you, “This is your background, based on our database.” Well, if something’s not in their database, they can’t tell you that it’s in your background.
Narrator: The D.T.C.s have less data about people of African and Asian descent than they do about people of European descent.
Fatimah Jackson: Most of the genetic testing that has been done, has been done on North Atlantic Europeans. So, our reference databases are biased.
Foeman: Why don’t we all just take a minute and open your results, and take a look at the map for the first time.
Narrator: FamilyTreeDNA has given Nick Pasvanis, whose parents trace their ancestors to Greece, Germany, England and Scotland, a detailed breakdown.
Nicholas Pasvanis: I’m 45 percent Southeastern European, which is about what I expected. I’ve always felt like I was just a general European mutt, and that’s pretty much what the map shows.
Richardson: So, I was wondering, when I got it, like, if it would say if I was Black. And I am 94 percent West African, so, yeah, I’m pretty Black.
Narrator: But Cherry Richardson’s African bubble provides little detail.
Hana Wiessmann and Viola Wang, who were both born in China, have even bigger bubbles.
Hana Wiessmann: I mean, I have just these giant bubbles, and they’re like, “You’re super Asian.” Like, I kind of already knew that, so…
Viola Wang: Basically, people who have huge bubbles are considered the minorities.
Jackson: And it’s unfortunate, because it perpetuates a kind of Eurocentrism that has tainted our scholarship, that is a foundation for notions, false notions of white supremacy. And it highlights the disparities that are currently prevalent throughout science and particularly in genetics.
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