How Responsible Are We for Our Morals, or Lack Thereof?

Most of us realize that the world does not revolve around us, and that we have to consider other people. Still, the amount of selfishness and empathy varies widely from person to person. You probably know people who are just plain awful even though they know better. But what if evil and selfishness were all you ever knew, and it was completely normal in your world? You'd still be a complete failure as a person, but was that your fault, or the fault if the way you were taught? In other words, how responsible are people who never learned ethics or morality?  

You'd be hard-pressed to find examples of people who never had the opportunity to develop a moral structure, but that brings up the subject of psychopaths, who have a personality disorder and would like you to think it's not their fault. That subject isn't discussed here. Rather, this is a thought experiment about the responsibility of evil, which philosophers have argued about for thousands of years.