What do you call a little white girl who can run faster than her brothers ? A virgin.
I don't really understand what you're trying to say. Are you saying that white people commit incest?
I'm just joking, but I do think it's true.
Incest is a serious matter and not something to joke about. It's wrong to assume and perpetuate that all white people are engaging in incestuous relationships with others.
I'm just joking, but stop ruining my jokes.
I'm just making you aware of the rude implications of your offensive joke. Not everyone is going to find that funny, especially as it is generalizing a whole population falsely and inappropriately. Why not try making safer jokes that people would approve of?