Pretty much it reduces to this: if a% of b == c, and if d% of e == b, then a% of d% of e == c 10% of 100 = 10, 10% of 1000 = 100, 10% of 10% of 1000 = 10 if 90% of autistic people are atheists, and if 10% of people with a certain gene are autistic, then at least 90% of 10% of people with that gene are atheists. I can tell that I am correct in purely mathematical sense but perhaps it doesn't apply to non-mathematical reality? For example: if 10% of cats are brown, and if 10% of my animals are cats, then at least 10% of 10% of my animals are brown. I imagine that probabilistically this would be true, but it is still entirely possible for all of my cats to be white.