|"Bully" - the Movie|
Being raised in a home where there is an apparent lack of self-control by family members can cause children to want to exercise control over something outside of their home life. Growing up my brother had a friend that was constantly trying to assert his dominance over the other boys his age. He would regularly throw toys at them and tell them how stupid they were. Eventually we found out that his father had zero self-control at home, and while he was obedient at home he projected these pent-up feelings on his friends that were more submissive. This desire to gain control can manifest itself in the form of bullying peers that are perceived as weaker and thus easily dominated.