Taking cues from family and media, young boys teach their peers how to perform masculinity, to their detriment.

Noah Berlatsky interviews Judy Chu, author of When Boys Become Boys about her research into the lives of young boys, the struggle between their need for closeness, and the pressures to abandon close friendships.  https://www.theatlantic.com/health/archive/2014/06/how-boys-teach-each-other-to-be-boys/372246/