Her genetic analysis was done by Carlos Bustamante, a geneticist at Stanford University and a MacArthur fellow who has served as an adviser for the commercial DNA testing companies 23andMe and Ancestry.com.
“This is a pretty convincing report that there is a Native American ancestor sometime during the early 19th century,” said Beth Shapiro, a professor of ecology and evolutionary biology at the University of California, Santa Cruz.
While the reliability of commercial ancestry testing kits has been called into question by the media and consumers, Christopher Brown, an assistant professor of genetics at the University of Pennsylvania’s Perelman School of Medicine, said that broader, continental-level ancestry testing is “pretty straightforward.”
Pinning down ancestry to a country or specific tribe, on the other hand, is more complex. DNA testing is done by comparing an individual’s DNA with samples that are already in the database pool, so it helps to have a large reference panel to compare with. (Testing can more accurately determine if someone has European ancestry than German ancestry, for example.) Since there isn’t extensive data on individual Native American tribes, it’s more difficult to assign ancestry to a particular tribe. In short, the more specific you get, the more inaccurate you get.
Beyond scientific accuracy, there are thornier ethical and identity questions at play.
“The elephant in the room here is whether DNA testing tells us anything about heritage or ethnicity,” Simon Gravel, an assistant professor of human genetics at McGill University for whom Bustamante served as a postdoctoral adviser.
“My personal opinion is that DNA testing should not be the way in which we determine ethnicity.”
DNA evidence of Native American ancestry is very different from having an affiliation to a specific nation and is out of step with the way tribe members define membership.
“Tribal governments establish regulations that do not use genetic ancestry tests but other forms of biological and political relationships to define our citizenries,” Kim Tallbear, an associate professor at the University of Alberta and a member of the Sisseton Wahpeton Oyate tribe, posted in a statement on Twitter.
“Indigenous definitions of who we are continue to be background noise in Democrat vs. Republican party warring,” she added.
Furthermore, the broad distinction of having evidence of a Native American ancestor doesn’t boil down to a specific tribal connection.
“A DNA test is useless to determine tribal citizenship. Current DNA tests do not even distinguish whether a person’s ancestors were indigenous to North or South America,” Chuck Hoskin Jr., the Cherokee national secretary of state, said in a statement. “It is not evidence of tribal affiliation.”
Warren clarified on Twitter that she did not take the test to claim Cherokee membership.
“DNA & family history has nothing to do with tribal affiliation or citizenship, which is determined only — only — by Tribal Nations,” she wrote. “I respect the distinction.”
Making cultural identifications based on genetics could be a slippery ethical slope, according to Arthur Caplan, the founding director of New York University’s division of medical ethics.
“I consider the social more powerful than the genetic in those situations,” he said. “It could be as much cultural as anything having to do with genetics.”
He said he worried that making genes a key part of identity could lead to their being used as a basis for discrimination or pushing an individual out of a group. (White supremacists have attempted to use genetic testing to bolster claims about their white heritage.)
“If you’re a fifth-generation tribal leader and your genetic test doesn’t quite cut it, are they going to say, ‘Oh, not Native American, sorry?’ he asked.
Warren’s release of her DNA report followed President Donald Trump’s challenging her claims of Native American heritage this year, mockingly calling her “Pocahontas” and claiming that she used her claim to that ethnicity to advance in her law career. He also said he would donate $1 million to a charity of her choice if she took a DNA test proving that she has Native American ancestry.