
This illustrates that the media and elites have been using this ploy for a long time. I am talking about the Afghan girl photograph, or the foregrounding of blonde and blue-eyed Yezidi children. Recently I expressed some irritation on Twitter when there was a prominent photograph of a hazel-eyed Rohingya child refugee being passed around. Something like 1 in 500 people in that region of the world has hazel eyes! That couldn’t be a coincidence. Race matters when it comes to compassion.

According to 23andMe’s database about 1 out of 10 white Southerners has African ancestry at the 1% threshold. It would be even more if you dropped to closer to 0.5%. And the DNA ancestry here understates the extent of what was going on: at about 10 generations back you are about 50% likely to inherit zero blocks of genomic ancestry from a given ancestor (assuming no inbreeding in the pedigree obviously). And this is exactly when a lot of the ancestry that is being detected seems to have “entered” the white population. In other words, for every person who is 1% African and 99% white American, they have a sibling who is 0% African and 100% white American, even though genealogically they share the same ancestors. Dropping the threshold to closer to 0.3%, and considering that even in the South there was migration from the North, and to a lesser extent Europe, after the Civil War, I wouldn’t be surprised if models of admixture inferred from the distributions we see indicate that over half the lowland Southern white population likely had genealogical descent from a black slave.

The reason is obvious in the context of American history. Thomas Jefferson’s slave Sally Hemings had three white grandparents and one African slave grandparent. Several of her children are recorded to have been totally European in an appearance, and all except one passed into the white population (the two eldest married well into affluent white families in Washington D.C.). Passing as white was a way to escape the debilities of black status in the United States.


But the attitudes toward racial segregation and mixing took decades to harden. Martin van Buren’s vice president, Richard Mentor Johnson, was well known to have had a common-law wife, Julia Chinn, who was a slave. He recognized his two daughters by her. He was vice president from 1837-1841 in the more racist of the two American political parties of the time. It is hard to imagine this being a viable “lifestyle” choice for someone of this prominence in later decades (after Julia Chinn’s death Johnson continued to enter into relationships with slaves).

Which brings us back to what was happening in the decades around 1800. Racism was a fact of life, necessitating the need for passing. But, beliefs about racial purity and the one drop rule had not hardened, so it would not be surprising to me that it was much easier for slaves or ex-slaves with mostly European ancestry to change their identity. Perhaps white Americans of that period were simply less vigilant about someone’s background because they were genuinely less concerned about the possibility that their partner may have had some black ancestry, so long as they looked white.
As the databases grow larger we’ll get a better sense of the demographic and genealogical dynamics. My suspicion is that we’ll see that there wasn’t much diminishment of gene flow into the black-identified community over the past 200 years, as much as the fact that hypo-descent, the one-drop rule, became so powerful in the between 1850 and 1950 we can confirm that passing declined, before rising again in the 1960s as whites became less vigilant due to decreased racism.
* As a middle class New Englander John Adams obviously was no aristocrat, but he was no populist either.

