Genetic Ancestry of Americans Varies by Region Across the United States

The United States is known as a melting pot of different cultures and genetics. Yet how the genetic ancestry of these populations varies across different regions in the U.S. has been neglected by scientists-until now. Researchers analyzed the genomes of Americans to provide novel insights into the subtle differences in genetic ancestry across the U.S.

Over the past 500 years, the United States has been on ongoing site of mixing of Native Americans, European settlers, and Africans. While much of the world has been genetically characterized, though, North America has received far less attention due to its complex ancestry patterns.

In order to learn a bit more about the genetics of the U.S., the researchers analyzed DNA sequence variations called single-nucleotide polymorphisms in the genomes of African Americans, Latinos and European Americans. These individuals participated in 23andMe research by submitting saliva samples and consenting for data to be used for research, and by completing surveys.

"Our study not only reveals the historical underpinnings of regional differences in genetic ancestry but also sheds light on the complex relationships between genetic ancestry and self-identified race and ethnicity," said Katarzyna Bryc, the lead study author, in a news release.

In this case, the researchers found that the genetics reflect historical events, such as waves of immigrations. For example, Scandinavian ancestry can be found in trace proportions in most states but comprises about 10 percent of ancestry in European Americans living in Minnesota and the Dakotas. In addition, people actually identified roughly with the majority of their genetic ancestry, contrary to expectations.

"These findings suggest that many individuals with partial African and Native American ancestry have 'passed' into the white community, thereby undermining the use of cultural labels that separate individuals into discrete, non-overlapping groups," said Bryc. "Taken together, our results suggest that genetic ancestry can be leveraged to augment historical records and inform cultural processes shaping modern populations."

The findings are published in the American Journal of Human Genetics.

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