"We grow into our rationality as caterpillars grow into butterflies. If the caterpillar eats enough leaves, it will (eventually) grow wings. And if the child gets enough experiences of turn taking, sharing, and playground justice, it will (eventually) become a moral creature, able to use its rational capacities to solve ever harder problems. Rationality is our nature, and good moral reasoning is the end point of development."
~The Righteous Mind: Why Good People Are Divided by Politics and Religion by Jonathan Haidt