People's fascination with genetic testing is not going away any time soon (Credit: Pexels)
When Sen. Elizabeth Warren shared the results of a DNA test last fall as evidence of her Native American ancestry, she only fueled public backlash over her purported heritage.
Earlier this month, a Washington Post article — published days before Warren announced her 2020 presidential bid — revealed she had identified herself as “American Indian” when registering for the Texas bar exam.
Aside from sparking outcry from the Native American community, Warren’s DNA test stunt also highlighted two major downsides of consumer-based genetic testing: that it’s inaccurate and can offer people a contested sense of identity, experts say.
The science behind genetic testing is still in the early phases of development. For about $100, consumer DNA kits promise to reveal a long-lost identity or ancestry. But the common belief in such an outcome is based on faulty assumptions about what the tests actually tell us. Rather than nailing down the absolute origins of one’s bloodline, these tests simply reveal where similar DNA has been found in different parts of the world.
The problem is similar DNA isn’t an accurate tool for revealing one’s ancestry, according to Jennifer Raff, an anthropological geneticist at the University of Kansas who specializes in population genetics. And it certainly not synonymous with identity, Raff says.
“Culturally, we have been taught to conflate identity with ancestry,” she says. “The recent rise in popularity of at-home genetic testing reinforces that misconception.”
Consumer-based genetic testing companies such as AncestryDNA, 23andMe and MyHeritage started to emerge as early as 2006. But it wasn’t until 2017 that the number of people taking these at-home DNA tests reached 12 million people worldwide, according to industry estimates, most of whom are based in the U.S.
Raff explains the U.S. interest in genetic testing is due to many American families migrating here over the past two to three centuries, whether voluntarily or involuntarily, and these tests seem to offer a way of understanding family history before arrival in the U.S.
However, in terms of what these DNA test kits can offer, Raff says, “[their] accuracy depends on what questions you’re asking.”
Once test-takers have swabbed the inside of their cheeks and sent off their DNA sample to the corresponding lab for testing, scientists can accurately identify the person’s genetic relatives, or other people who have similar genetics, and where they live today. But that’s still not the same as ancestry — just because a genetically similar group of people tends to live in one area today doesn’t mean that’s where it originates.
“It doesn’t necessarily tell you where your ancestors came from,” Raff says. “We know that populations move around and that genetic history is not static.”
Another factor that dilutes the accuracy of commercial genetic testing is that the companies only have access to the DNA samples of people who have taken the test — the majority of whom are of European descent, according to a study published last year in Genome Biology.
“What these tests are doing is comparing test takers’ DNA and genetic variants to samples from other people that the company has access to, and are looking for shared genetic variants,” says Deborah Bolnick, an anthropologist at the University of Connecticut whose research focuses on human genetic variation.
Each company has a different set of DNA samples, and therefore a different database. As their database expands, companies often update people’s results.
When 36-year-old Kyla Cathey first got her DNA tested at AncestryDNA, it was out of personal interest in her genealogy. AncestryDNA put her ancestry at 18 percent Western European, including British and Scandinavian roots, and classified the rest in broad Asian categories. So Cathey decided to purchase another test with a different company, 23andMe; it returned different results, reporting she was 32 percent German and French, with South Asian and Filipino DNA.
Then, AncestryDNA updated its database, and sent her revised results — 88 percent English and removing her Asian and Scandinavian results altogether. This updated result confused Cathey, because even though the Scandinavian percentage had been previously listed as small, it was presented as “high confidence.”
“I could see the percentages changing, but why did everything disappear?” Cathey says. “If those regions were there on the first set of results, where did they go?”
Raff says that people viewing their results should keep that in mind that any particular company’s database might not include many genomes from a specific ancestry.
“They drive their data from their participants. Europeans are way overrepresented relative to [other places,]” she says.
In an email statement, a spokesperson from 23andMe wrote, “Our ancestry reports are a living analysis and are ever-evolving, and as our database grows we will be able to provide customers with more granular information about their ancestry and ethnicity.” They went on to say that “consumers are discovering they can learn so much about their ancestry and ethnicity through their DNA. They can learn new things about their heritage.”
Bolnick says that the way these DNA tests are marketed reinforce the misconception that they will reveal a person’s ethnicity or race; in reality, that’s not the case.
“The racial or ethnic groups that we recognize in American society today are not based in our biology or DNA,” Bolnick says. “The groups we identify socially don’t map in genetic variation in humans; there are no particular genetic markers.”
Race generally refers to a person’s biological makeup while ethnicity is more related to ancestry and culture. However, society’s modern perception of race sorts people into categories based on an aggregation of certain traits.
And just as the controversy surrounding Senator Warren’s “heritage” has plagued the candidate for months on end, Bolnick thinks the American fixation on genetic testing will persist.
“We’re really fascinated with DNA and genetics. We tend to see DNA as powerful, influential,” she says.
If race isn’t coded in our genetics, a genetic test alone can’t tell us what group of people we actually belong to. But people’s desire to seek identity and a sense of belonging still leads them to these tests.
“Many people will continue to seek out genetic answers to these kinds of questions even though genetic answers don’t exist to these types of issues,” Bolnick says.
Raff agrees, saying that from a scientific perspective, Warren’s results do show clear Native American ancestry. The problem, Raff says, is that tribal membership, like race and ethnicity, “isn’t dependent on genetics.”