I almost got into discussing determinism here, but I've already talked about that a lot here already. What's interesting about the language we create is how it shapes our thoughts and in turn, our actions. If an entire community was made up of "assholes" would they still use that word? Would that word even have meaning anymore? If assholery was expected and rewarded within a community, wouldn't that even be assholery anymore?
But yeah, if all we are taught is how to harm others, we do have to learn new skills in order to function well as a social species. At least, that's what I see throughout history. Being a bad actor seems to be irrational over a long enough timescale. As a social species, we harm ourselves when we harm others.