Back in the 1980s, Judith Smetana and colleagues discovered that very young kids could discriminate between genuinely moral principles and mere social conventions. First, the researchers asked about everyday rules—a rule that you can't be mean to other children, for instance, or that you have to hang up your clothes. The children said that, of course, breaking the rules was wrong. But then the researchers asked another question: What would you think if teachers and parents changed the rules to say that being mean and dropping clothes were OK?
Children as young as 2 said that, in that case, it would be OK to drop your clothes, but not to be mean. No matter what the authorities decreed, hurting others, even just hurting their feelings, was always wrong. It's a strikingly robust result—true for children from Brazil to Korea.