Here is an article I found online....
How can we understand this connection?
There is a widespread view that men are "naturally" prone to violence because of their genetic inheritance. Some people claim that men are made more aggressive by their hormones, especially by testosterone. Some think it is a matter of the "male brain" working in different ways than the female brain.
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LINK: http://www.undp.org/rblac/gender/menandviolence