Some cultures permit the killing of newborns, whereas others debate abortion of the unborn.
Some cultures disapprove of premarital sex, whereas others encourage it as part of a healthy sexual education. The gravest error of biologists speculating about the origin of morality has been to ignore this variability, and to downplay the learned character of ethical principles. Possibly we are born, not with any specific social norms, but with a learning agenda that tells us which information to imbibe and how to organize it. We could then figure out, understand, and eventually internalize the moral fabric of our native society. Because a similar learning agenda seems to regulate language acquisition, I will speak of moral ability as a parallel to language ability.