To follow up on the previous post on the evolutionary benefits of kindness, this essay by Marc Hauser describes some of the science that indicates that morality is innate. Not religious affiliation, gender, nationality nor political views affect how people respond to moral dilemmas.
“We tend to see actions as worse than omissions of actions.” People tend to believe that deliberately hurting a healthy person to save one or more others is morally repugnant if the others would only be hurt by your inaction.