Sprinting is THE sport of Jamaica. Distance running is THE sport of East Africa. As someone who trains somewhat competitively for marathons in a group, I can

Sprinting is THE sport of Jamaica. Distance running is THE sport of East Africa. As someone who trains somewhat competitively for marathons in a group, I can tell you that having people of similar ability to train with has a huge impact. As does having soft surfaces to run on and good weather. Genetics may be in play, but it isn't the only thing in play.