There are two different things. Moral codes are agreements made with your culture. Some moral codes look silly from outside, like eating rules and superstitions.

But the sense of right action inherent in the individual goes beyond moral codes and addresses the path to optimum well being. That is the sense of ethics.

Enlightened self-interest reaches out from the self, embraces the groups (family, civic, organizational or national) one is part of, and from there addresses life itself in all its manifestations and seeks the best path for all those considerations.

They are not derived from "cultural agreements" except secondarily, as a guideline to not distressing others in your culture.

A