Children have witnessed violence in the media since early ages, and the images they see show violence in general positively. Children can also be exposed to violence at home, at school and in the environment they live in. Inadequate skills to resolve conflicts and alcohol and drug abuse also increase violent behavior in adolescents.
Go see the way your child watches on TV, see them in movies and watch them on the internet and talk to him to resolve disputes. Also, make sure that your own behavior is an example of nonviolent behavior.