Exceptional talents are the result of the combination of rare recessive genes which rarely match in children.Then it begs the question about why genius isn't passed down from generation to generation, doesn't it?
Why was Wolfgang Mozart's son a mediocre composer. (And his other son has no music talent at all.)
Why were Albert Einstein's sons, not great physicists? One of them, in fact, had schizophrenia and spent much of his life institutionalized.