I say Barton is a fool because I am certain it happened in my family. Years ago there was a black Federal Judge on the short list for the Supreme Court with the same last name as mine. When I saw a picture, I was shocked that he looked like he could have been my father's black brother. My father had a very distinctive look, so much so that it could not have been anything but shared DNA. In case you may wonder, yes, my relatives held slaves as documented in census records and wills.
I studied under a prominent anthropologist in a PA. state university, and it was established in that community that although Jefferson DNA in Sally Hemming’s children was present, it was impossible to say Thomas Jefferson was the father. He posted the findings, taken from a per reviewed paper on the department’s bulletin board, which I saw with my own eyes.
The DNA “test” determined that some one in the Jefferson line was the father. TJ’s brother was in charge of the plantation while TJ was doing government service. When he got back to Monticello, he discovered his brother was raping slaves and sent him off. He also discovered that this brother had bankrupted him. This is another urban myth about TJ.