Understanding African American European Ancestry

It has been a common assumption within the African American community that European male slave-owners had sex with African female slaves during the American slavery period. This period started around 1619 when Africans were brought to Jamestown, Virginia to help with tobacco crops; and ended officially with the passage of the Thirteenth Amendment in 1865 (History.com).

In one article, USA Today estimated that “About 30% of black Americans who take DNA tests prove to be descended from Europeans on their father’s side (USA Today 2/2/06, pg. 4A).

How can we confirm the above assumption? The answer is DNA. More specifically, DNA Haplogroups. Haplogroups can tell you where a line of your ancestors originated from thousands of years ago. There are two types of Haplogroups: Y-chromosome (Y-DNA) haplogroups and mitochondrial DNA haplogroups. “Y-DNA is passed solely along the patrilineal line, from father to son, while mtDNA is passed down the matrilineal line, from mother to offspring of both sexes. Neither recombines, and thus Y-DNA and mtDNA change only by chance mutation at each generation with no intermixture between parents’ genetic material” (Wikipedia).

Since only males have Y-chromosomes, women can’t trace their ancient paternal ancestors. They have to have one of their male relatives do it. Conversely, even though mothers pass their mtDNA to both their male and female offspring, only females can pass their mother’s mtDNA to their own children. So males may have to have one of their female relatives trace their ancient maternal ancestors.

Thus, African American males can do a Y-DNA test to find if they have an ancient white male ancestor on their father’s side but not on their mother’s side. But, African-American females can perform an mtDNA test to determine if they have an ancient white female ancestor on their mother’s side. The exception to this is that some DNA companies are able to use their autosomal DNA test to determine a male’s ancient maternal ancestor (using the X-chromosome the male receives from his mother).

Therefore, using a Y-chromosome or autosomal DNA test we can determine if an African American male has an ancient European male ancestor. We can also use an mtDNA or autosomal DNA test to determine if an African American female has an ancient European female ancestor.

So if an African American’s paternal and maternal ancient ancestors are traced to Africa we know that they did not interbred with Europeans and thus, did not interbred with European slave owners during the African slave period in the United States.

Conversely, if an African American male’s paternal haplogroup is European, we know that at some point a European male had a male child with one of his African female ancestors. We also know that if an African American’s material haplogroup is European, then at some point a European female had a child with one of their African male ancestors. We can speculate that for African Americans, this interbreeding occurred during slavery and was non-consensual for the most part. We can also speculate that sex between European females and African males was rare during slavery times as this union would have resulted in the killing of the African male if it was discovered.

Let’s look at a simple example of how this haplogroup stuff works. Figure 1 provides an example to show how an African American male can end up with a European paternal haplogroup:


In Figure 1 the Yp letters represent the Y-chromosome of the male’s paternal line and the Xm letters represent the mitochondrial X-chromosome of the female’s maternal line.

1st Generation
The European couple have the paternal and maternal IDs of YP1 and XM1 respectively while the African couple have the corresponding paternal and maternal IDs of YP2 and XM2.

2nd Generation
The 1st Generation European couple have a son who becomes a slave owner in American. This son carries his father’s Y-chromosome (YP1) and his mother’s X-chromosome (XM1). This European son has sex with the 1st Generation African couple’s daughter. This daughter carries her mother’s X-chromosome (XM2) but since females don’t have Y-chromosomes, her African father’s YP2-chromosome is not passed to her.

3rd Generation
The European male Slave-owner and African American female slave have a boy and a girl. The boy carries his European father’s Y-chromosome (YP1) and his African American mother’s X-chromosome (XM2). He marries an African American woman (XM3). The girl carries her African American mother’s X-chromosome also but her European father’s Y-chromosome is not passed to her. She marries an African American man.

4th Generation

As we get to the 4th generation we will find that only ancestors we can trace from the 1st generation are the male with Y-chromosome YP1 (YP1, XM3) and the female with X-chromosome XM2. The 4th generation YP1 male is the direct descendant of the 1st generation European male and the 4th generation XM2 female is the direct descendant of the 1st generation African female.

The above example shows that if a European male Slave-owner had an offspring with an African female slave the following would be true:

  1. All direct male descendants would carry the European male Slave-owner’s Y-chromosome
  2. All direct female descendants would carry the African female slave’s X-chromosome.

In my own case (I am an African-American male), using DNA tests I found out that I have a European paternal haplogroup and an African maternal haplogroup meaning that I am descended from Europeans on my father’s side and Africans on my mother’s side (All my post Slavery ancestors seem to be African American).

The Genetic Literacy Project found: “Broadly, the genomic analysis found that on an average the African-American genome was 73.2 percent African, 24 percent European and 0.8 percent Native American”. These numbers vary somewhat depending on the different companies who have performed these estimates.

In addition, an article by Henry Louis Gates Jr (Exactly How ‘Black’ is Black America?) found “A whopping 35 percent of all African-American men descend from a white male ancestor who fathered a mulatto child sometime in the slavery era, most probably from rape or coerced sexuality.”

Are you one of them? DNA haplogroups have the answer.

If you are interested in tracing your family history see the below resources:

Organize Your Genealogy: Strategies and Solutions for Every Researcher