Yeah, sports are believed by many to be an area where blacks have an advantage, if anything, (white men can't jump, anyone?) and obviously it's easier to get involved in sports than it is to go to the best schools, so socioeconomic circumstances are probably the biggest factor. Opportunity breeds players; just look at the baseball factory that is the Dominican Republic. If you're a coordinated young man from the Dominican Republic, someone's going to want to put a bat in your hand and so you end up with a surprising number of the world's pro ball players. There's also the fact that if you're the slightest bit black or even look kind of black, people tend to think of you as black, which is sort of funny considering how many athletes are actually of mixed heritages. I bet your average person off the street will always at least know "black" when asked about Tiger Wood's background, but the guy is also Thai and Chinese in equal measure, with a dollop of Dutch and Native American thrown in for variety. So you have to consider that the way we tend to categorize people skews things from the outset.
Which leads me to another point: there is probably a bit of a genetics involved, but that's different from saying blacks are better at sports in general. After all, the highest tier athletes are almost statistical outliers by definition. Michael Jordan was Michael Jordan in part because he had some physical gifts that are atypical of any group. But that said, Africans and people of recent African descent come from a population that features a much higher degree of genetic diversity than the populations the rest of us come from. After all, other ethnic groups are essentially just relatively small sub-samples of some original African population. So, if there is some magical confluence of traits out there that can result in say, a Shaquille O'Neal, then it's likely to be present in the African American population even if they are in the minority. That still leaves most blacks muddling around in mediocrity land with the rest of us, however, so skin color is still a horrible way of predicting success in well, anything.
