A decent government with an effective, but not gratuitously violent, police force and a fair court system are essential. This deters and incapacitates psychopaths, bullies and hotheads - and if it earns the confidence of the people, they don't have to become violent in self-defence.

Morality, then, is not a set of arbitrary regulations dictated by a vengeful deity and written down in a book; nor is it the custom of a particular culture or tribe. It is a consequence of the interchangeability of perspectives and the opportunity the world provides for positive-sum games.

Without goals the very concept of intelligence is meaningless

If you aren't just brought up in your tribe but interact with other people either directly or vicariously, through journalism and literature, you see what life is like from other points of view and are less likely to demonize them or dehumanize others and more likely to empathize with them.

Since violence is largely a male pastime, cultures that empower women tend to move away from the glorification of violence and are less likely to breed dangerous subcultures of rootless young men.

As technology accumulates and people in more parts of the planet become interdependent, the hatred between them tends to decrease, for the simple reason that you can't kill someone and trade with him too.

So no, it's not all in the genes, but what isn't in the genes isn't in the family environment either. It can't be explained in terms of the overall personalities or the child-rearing practices of parents.