It is true Jefferson, like others was flawed. Show me someone who isn’t. It would take a great man to give up his slaves back then, the source of his wealth, to become poor, to lose his home, his way of life, for his ideals. There are some throughout history who have done so, most, at least in Europe, are usually considered saints. I do not fault Jefferson for being human, merely that it is important to point out the difference between living the theory and doing the practice.
As for DNA, it is to my knowledge, that no DNA has yet to be taken from Jefferson, himself. So while they are family members, just who was the father, may still be in doubt. Any info to the contrary would be gladly welcomed.