Mitochondrial DNA is inherited from the maternal line. A mother passes it on to all of her children.
There never has been proof that Thomas fathered Hemings’ children. Only that a Randolph male did. There were several of those who could have been the father.
His brother had a local reputation of helping himself to the noncontract female help!
The point of this article is that we have the basis *you* point out from the mitochondrial DNA, but with the hair we now have DNA that is *not* mitochondrial. If you want to believe Tom had Randolph’s hair in his book, that’s fine, but the claim here is that we’re start with Tom’s actual DNA, not tracing mitochondrial DNA through matrilineal descent.