Our concept of morality seems based on the genetic endowment of our species.

Source: "The Moral Life of Babies," Paul Bloom, The New York Times Magazine, May 3, 2010.

"Morality, then, is a synthesis of the biological and the cultural, of the unlearned, the discovered and the invented. Babies possess certain moral foundations — the capacity and willingness to judge the actions of others, some sense of justice, gut responses to altruism and nastiness. Regardless of how smart we are, if we didn’t start with this basic apparatus, we would be nothing more than amoral agents, ruthlessly driven to pursue our self-interest. But our capacities as babies are sharply limited. It is the insights of rational individuals that make a truly universal and unselfish morality something that our species can aspire to."