MOST OF THE experts who have studied teen violence agree that the violent acts committed by teenagers— assaults, shootings, armed robberies, rapes—cannot all be explained by a single reason. Reporting that a violent young person is bad, irresponsible, lazy, or immoral gives little insight to the variety of reasons and influences behind the behavior. To begin to understand what is most likely to make a teenager capable of brutality and what conditions are most likely to trigger juvenile violence, it is necessary to look deeper into the lives of violent teens, the society that surrounds them, and the statistics of their crimes.

The "nature versus nurture" controversy

Even with all the statistics and studies of teen violence, experts disagree on some of the fundamental notions about the causes of teen violence. One of the longest...