I done my best to teach my daughters about testosterone poisoning and its dangers.
The male inclination for violence has a lot to do with testosterone, which is most plentiful in young men who, in their natural habitat, fought other males to impress women. (You can head down to Fort Lauderdale during Spring Break to document this phenomenon yourself.)
Steven Pinker writes in The Better Angels of Our Nature, his sweeping history of violence, that “to the extent that the problem of violence is a problem of young, unmarried, lawless men competing for dominance, whether directly or on behalf of a leader, then violence really is a problem of there being too much testosterone in the world.”
Interestingly, one of the things that is most likely to make men less violent is getting married, proving that Clinton is right when she says that women have a pacifying effect. What public policies should flow from all this is a topic for another day.