There are different types of muscle tissue. One of those is made for long steady force. Another one is for a fast force, like sprinting. This is partially determined at your birth due to genetics. It is also impossible to train both, you can't be a top sprinter and a top marathon runner. When you train one the other gets "weaker".
If you look at places where the best black sprinters come from you'll see that its from a small area, for example Jamaica. This has to do with the genes which stay in this area.
But you'll see other sports where white people dominate.
By the way i don't think its a stupid question.