It is stupid to think genetics do not play a huge role determining athletic success. It is also stupid to think that a variety of other factors do not play a huge role in determining athletic success.
Genetics is not synonymous with race. I guess Jamaicans and Kenyans would both be black, but it doesn't say much. However the distinct genetic makeup of Jamaican sprinters and Kenyan long distance runners certainly has a lot to say about their likelihood for athletic success. Jamaican long distance runners are garbage and Kenyan sprinters are garbage.
It is also depends greatly on the sport. Football, or more specifically,cornerback certainly demands more than just explosive quick twitch muscles, though they don't hurt.