Why are some races good at certain sports?

Is it in their genes, ethnicity or because of natural/environmental factors? cubans are great in amateur and even pro boxing , jamaicans are great in sprint, africans in long distance running, chinese in diving,, europeans and hispanics in soccer, japanese and koreans in baseball, pinoys in billiards, russians in chess. Is it in their genes, ethnicity or because of cultural, social, natural or environmental factors?