"Exactly How ‘Black’ Is Black America?"

"for our African-American male guests, there has been still another astonishing fact revealed about their paternal ancestry -- their father's father's father's line -- through their y-DNA: 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. In other words, if we tested the DNA of all of the black men in the NBA, for instance, just over one-third descend from a white second or third great-grandfather. In my own case, he was my great-great-grandfather, and he was most probably of Irish descent, judging from our shared y-DNA haplogroup.

I find two things quite fascinating about these results. First of all, simply glancing at these statistics reveals that virtually none of the African Americans tested by these DNA companies is inferred to be 100 percent sub-Saharan African, although each company has analyzed Africans and African immigrants whodid test 100 percent sub-Saharan in origin. Ranges, of course, vary from individual to individual. Spencer Wells, director of National Geographic's Genographic Project, explained to me that the African Americans they've tested range from 53 percent to 95 percent sub-Saharan African, 3 percent to 46 percent European and zero percent to 3 percent Native American. So there is a lot of genetic variation within our ethnic group, as is obvious to anyone even casually glancing at black people just walking down the street.

What this means is that even the most phenotypically "African" (or what used to be called "Negroid") African Americans have dramatically significant levels of European ancestry, a fact that would have astonished many of our forebears, both black and white. It is also a fact that astonishes the guests onFinding Your Roots. And this finding is important because it deconstructs the very American notion of biologically "fixed races" that our society inherited from the racist pseudoscience of the 18th century and drew upon to justify slavery and the property rights of masters who fathered children with their slaves."

http://www.theroot.com/articles/history/2013/02/how_mixed_are_african_americans.4.html