"Certain surnames are predominantly black?"
They are where I live. If you meet a white guy with the last name Washington or Jefferson, let me know. There are other surnames in this part of the country that are predominanly black. Whoopie. So what?
Well, I don't live in your state, but there are lots of white-skinned folks where I am with last names of Washington and Jefferson.
I'll bet there are in your area, too. You just don't know them, so you play the stereotype game. How moronic a thing to say.