I'd be careful to keep in mind that this broad generalizations can be easily misinterpreted to mean that men are inherently aggressive. None of my male friends are more aggressive than my female friends. I realize that my sample is biased, but that's precisely my point: the generalization about male aggression is not nearly as universal as it sounds, which is why iI would word it differently. I would word it thus: a higher percentage of men than women become physically aggrressive. Women can be quite aggressive emotionally (just as men can be). That's still a form of aggression. And women can be physically aggressive, regardless of testosterone production. The only person who ever tried to smash my skull with a a hard rock was a drunk, ex-girlfriend who was a heavy alcoholic at age 22. Testosterone is one of many factors.