An analysis of his genome shows that 16% of his genes are likely to have come from a black ancestor of African descent. By contrast, most people of European descent would have no more than 1%.Based on Watson's own arguments, this means that he is 16 times more likely to say stupid things about race and intelligence than the average person of European descent.
The study was made possible when he allowed his genome - the map of all his genes - to be published on the internet in the interests of science.
“This level is what you would expect in someone who had a great-grandparent who was African,” said Kari Stefansson of deCODE Genetics, whose company carried out the analysis. “It was very surprising to get this result for Jim.” [Link]