I’m Creole. Why Do I Have South Asian DNA?

Tracing Your Roots: Several factors could explain a questioner's surprising genetic-testing results.

Lauren Williams with her mother, Andrea Williams
Lauren Williams with her mother, Andrea Williams

(The Root) — Genealogical DNA testing can yield very surprising results, as The Root‘s deputy editor just found out.

“My mother, who is Creole from Louisiana and identifies as black, had her DNA tested recently. The test results came back as positive for a region in India. She was very shocked and confused, because she had never heard of Indian ancestors and can’t trace any to Asia on her family tree. Is this a false positive?” –Lauren Williams

Probably not. Several reasons could explain why DNA results for a female Creole from Louisiana would show traces of ancestry from a region in India.

The testing company that your mother used, DNA Tribes, measures a person’s genetic profile across his or her genome, excluding the sex chromosomes, focusing upon 15 genetic markers. As the company says, “Values from all 15 markers are used to compute high-resolution population and world region matches” between you and geographic populations.

In your mother’s case, her “Native Population Match” results indicate that her DNA is most common in India. Indeed, in the company’s “Upper Caste (Andhra Pradesh, India)” population, she has a 70.42 Match Likelihood Index Score.

What does this mean? It means that your mom’s DNA profile is most common among these people, of all the people in the world; in fact, it is 70.42 times as common in this group of people in India as in the rest of the world! In another chart among your mom’s results, her “Global Population Match Results” — her “closest genetic relatives today and peoples whose blend of geographical ancestry” is most similar to her own — again, belong to the Upper Caste, Andhra Pradesh, India population.

However, these tests measure your mom’s deep ancestral origins, not necessarily “recent social or cultural affiliation with a particular ethnicity,” as the DNA Tribes website puts it. These results illustrate how human populations evolved, over the last 500 years, as well as over thousands of years, as recorded in your mother’s genome. Fascinating, isn’t it?

You see, people have ranged far and wide since leaving the cradle of humanity in Africa, so a population migration in the distant past could account for an unexpected DNA testing result today. Ancient peoples with genetic similarities whose descendants now live in India may have settled in the areas in which your mother’s ancestors were known to have lived. According to Migration Information Source, “In ancient times, Indian traders established bases around the Indian and the Pacific Oceans, especially in East Africa and Western and Southeast Asia.”

Being Creole suggests the possibility of some European ancestry as well. Long-ago migrations from the East into Europe could have resulted in your familial link to India (or a closely related population).