Traditional measurements of genetic ancestry rarely offer information on specific ancestors in a family tree. A new approach to genetic ancestry developed by Stanford researchers yields insight into African American history by providing estimates of the number of African and European genealogical ancestors in typical family trees.

Family trees, photo albums, and grandparents are often the go-to sources of information for people curious to know who their relatives were. Genetic ancestry is also a useful tool, but these measurements typically provide data on percentages of different populations in a person’s ancestry, not on specific people. Now, a new study led by researchers from Stanford and the University of Southern California introduces a new way to think about genetic ancestry, revealing information that approximates the number of people from a source population.

The researchers apply this new approach to the genetic and genealogical history of African Americans from the 1600s to the present to estimate the number of African and European ancestors who appear in a randomly chosen African American person’s genealogy. The authors provide context for their results by using a historical book written about several generations of the family of Michelle Obama, the former first lady of the United States, as an example.

Jazlyn Mooney, a former postdoctoral scholar in the Stanford School of Humanities and Sciences, now a Gabilan Assistant Professor of Quantitative and Computational Biology at USC, is the lead author. Noah Rosenberg, the Stanford Professor of Population Genetics and Society and professor of biology in the School of Humanities and Sciences, is the senior author. The study summarizing their results published July 6 in Genetics and is the cover story.

Here, Mooney and Rosenberg discuss their new approach and how it helps fill a gap in the ancestry of African American people descended from Africans forcibly transported to the United States as enslaved captives during the Transatlantic Slave Trade.

You can read more in an article by Holly Alyssa MacCormick published in the stanford.edu web site at: https://tinyurl.com/mrx3yn48.