Marc D. Hauser says morality is a product of biology, not religion:
For one, some of our moral instincts evolved during a period of human history that looked nothing like the situation today. In our distant past, we lived in small groups consisting of highly familiar and often familial individuals, with no formal laws. Today we live in a large and diffuse society, where our decisions have little-to-no impact on most people in our community but with laws to enforce those who deviate from expected norms. Further, we are confronted with moral decisions that are unfamiliar, including stem cells, abortion, organ transplants and life support. When we confront these novel situations, our evolved system is ill-equipped.
The second reason is that living a moral life requires us to be restless with our present moral norms, always challenging us to discover what might and ought to be. And here is where nurture can re-enter the conversation. We need education because we need a world in which people listen to the universal voice of their species, while stopping to wonder whether there are alternatives. And if there are alternatives, we need rational and reasonable people who will be vigilant of partiality and champions of plurality.