LOL. I think genetics played a big role in it, however that is changing. Soon black people will be the same as whites, since the weak are allowed to mate with each other and raise a family. Before it was Ronnie's grandma and Dillet's granddad having a family. Now Vince Goodrum can go off and have a kid with a fat chick if he wanted to. I am not saying he would, but that choice totally kills the chances of having a genetic athlete.
I could also go out and breed with a fat mexican woman, and the results would be similar.
Here in SC, I have seen relatively few black people with great genetics actually working out in gyms. I have seen them walking around, but not in gyms.