“My own family members were discussing whether it was appropriate to put that information on the 2020 census,” she said. “With the new write-in lines included beneath each check box, they wondered how detailed they should be.” While the 2020 census results on racial identification have not yet been released, Saperstein suggests that demographers may need to ask different questions in the future to “more clearly distinguish ancestral diversity from experiences of race that are shaped by structural inequality.”

“If we want to monitor current racial disparities with survey or census data, then we need information that relates more directly to experiencing discrimination,” she said. “Or we need to be clearer with people that when we’re asking about race, we’re asking about how you move in the world today and how other people react to you, which may not reflect the long line of your family history.”

Regions of origin

The study also showed that certain ancestries, including those that are often highlighted in genetic test results, were more frequently reported by GAT takers than by non-GAT takers. For example, all GAT takers were more likely to report Scandinavian ancestry, rather than a more general response like “Western European.” Respondents who identified as Black and had taken a GAT were significantly more likely to report sub-Saharan African ancestry.

To further understand how people describe their ancestry, the researchers included both “sub-Saharan African” and “African American” among the responses on their survey. Nearly all respondents who selected African American ancestry were U.S.-born (97 percent). The sub-Saharan African response was selected most by either foreign-born people who identified as Black or people who identified as Black and had taken a GAT. This produced a striking difference among Black-identified respondents who did and did not take an ancestry test: After taking a GAT, 56 percent reported sub-Saharan African ancestry compared with 13 percent among non-test takers.

The study found related reporting differences between those who had and had not taken a genetic test among people who identified as Hispanic. Non-test takers were more likely to report Central or South American ancestry; GAT takers, however, were more likely to report Southern European and/or American Indian heritage, in line with the legacy of Spanish colonialism in the Americas. In contrast, the researchers found that people who identified as white and had taken a GAT were less likely to report American Indian ancestry than their peers.

“To us, this showed that people were using genetic information as a more accurate ancestry response,” Johfre said. “Not only did they seem to be embracing more distant lineages in their responses, but also sometimes dropping responses that might not have been supported by the tests.”

The researchers found that when they asked questions in a different order, putting questions about ancestry before asking questions about race, some of the differences in racial self-identification they had seen among GAT takers were less pronounced.

Jill A. Hollenbach of the University of California, San Francisco, is a co-author on this paper.

This work was supported by a grant from the National Institutes of Health.

To read all stories about Stanford science, subscribe to the biweekly Stanford Science Digest.