> I believe people are good at heart; our primate instincts are a fine balance of close social and family bonding and often brutal violence

I detect a contradiction.

People have both kind and brutal tendencies. The fact that most societies encourage the kind ones and discourage the others suggests that "goodness" may outweigh "badness," but that still leaves the bad to be pretty damned bad.

Consider Nazis, ISIS, Assyrians, Soviet and Maoist Communism....

Everyone involved in these groups grew up in an orderly and presumably "nurturing" society.

And let's not even mention warfare, which might be nonexistent if humans were good at heart.