Elizabeth Warren and the Folly of Genetic Ancestry Tests

This week, Senator Elizabeth Warren of Massachusetts announced that geneticists had analyzed her DNA and proved her longstanding claim that she has Native American ancestry. Senator Warren had caved in to months of ridicule by President Trump, who mocked her using a racist term and ultimately refused to believe her “useless” DNA test.

The question is not whether her DNA analysis is accurate. It’s whether it can tell us anything meaningful about identity. The truth is that sets of DNA markers cannot tell us who we really are because genetic data is technical and identity is social. The science in question is a form of chromosome mapping similar to that used in the billion-dollar genetic ancestry testing industry in the United States. That testing draws on incomplete data about human genetic diversity.

In this case, the “reference set” included samples drawn from 37 people “from across the Americas with Native American ancestry.” Nevertheless, this genetic analysis did locate five chromosome segments that strongly suggest indigenous ancestry. In his report, the geneticist Carlos Bustamante of Stanford University cautioned that it did...