>>17946215 (OP)
Sex involves intimate contact, a transfer of bodily fluids, which leads to a high potential for disease spread, and it has an obvious relation to reproduction, which leads to us being innately disposed to having certain views regarding sex. You should expect races which are more concerned with the quality rather than the quantity of their offspring to have more restrictive attitudes regarding sex, as this assists them in ensuring they mate with the right partner. This is one reason why higher races such as the English are more sexually restrictive than lower races such as sub-Saharan Africans.
There is good reason to believe that the desire to police certain sexual behaviours is innate, but what that desire is directed towards seems to be determined, in significant part, by culture. Nowadays, our morality is determined by feminists and Jews, and as a consequence, reproductive sexual behaviours, such as sex with young fertile women, are highly stigmatized.