What might make a seventeen year old boy incapable of controlling his physical outbursts?

Not knowing what do: I don't want to make light of the possibility of psychiatric illness here, and that needs to be explored first. But many of that generation, growing up with violent video games, tv etc, do not know how to properly channel their emotions. Its ok to feel upset and angry - that makes us humans. But its not ok to be violent in expressing that. He has to be taught appropriate outlets his emotions.