An angry and/or absent father causes an angry son. Those boys bullied at home will have contempt for all perceived authority figures: teachers, coaches, gov't, parents, adults, and so on.
A boy that's disappointed, marginalized, ignored, abused, depressed, will burn with anger like lava erupting from a mountain.
The emotion of anger helps to tell what's hurting/wrong. Anger that boils in a pot too long becomes harmful and unhealthy for all involved. Anger unattended becomes bitterness and hatred for people--and one's self.
If you know of a boy or man that has issues with rage, please send him my way. I was The Anger Machine.