Why should I worry about black sheep among my ancestors? I am not responsible my ancestors' decisions or actions. In Bible times people didn't worry about that.
Bible era Jews knew much about their ancestors. Jesus knew of most of his ancestors all the way back to Adam and Eve. We may only know of our ancestors 2, 3, or 4 generations back, and even then we may know very little other than names and perhaps where they lived.
Bible era Jews knew the good and the bad about their ancestors. Now we hesitate to talk about anything negative. Why don't we want to acknowledge that our we and our ancestors are not perfect?
Perhaps we could learn something from the Bible era Jews who were able to tell their children the whole story about their ancestors including the bad stuff. There must be a way to tell the whole story without glorifying mistakes and shortcomings on one hand, or berating people on the other hand.