I don't think Louis CK cares too much about that kind of things. His ex-wife is black and his daughters are blonde, and that's just the way the show goes. Also, F. Murray Abraham has played three different characters throughout the show. Characters come and go. He has a brother in the show who has appeared a couple of times. It has also been shown that he has two sisters (one of them played by Amy Poehler) but both of them have only appeared once and they're never mentioned again.
Now that I remember, there's one episode that I don't remember very well, in which he has to take care of his niece and I think her mother is a different sister.
So yeah, I don't think Louis CK cares too much about that kind of continuity or logic.

I don't watch the show, but read about it, and he basically just chose to have a black ex-wife in the show because he felt like ithe didn't really give any specific reason though.

ive sort of skipped around watching different episodes. but one thing I did notice is that his ex-wife (in the show) is black, & his kids are white.
are they adopted in the show? are they their biological kids? is Louis just making fun of the situation?
has this been explained at all?