In part because youth brains, particularly their frontal cortices, haven't fully developed yet, and that lack of development contributes to the ways young people get into trouble. Via LiveScience's "Top Ten Things You Didn't Know About You" (click on #5),
We know that hormone-fueled changes in the body are necessary to encourage growth and ready the body for reproduction. But why is adolescence so emotionally unpleasant? Hormones like testosterone actually influence the development of neurons in the brain, and the changes made to brain structure have many behavioral consequences. Expect emotional awkwardness, apathy and poor decision-making skills as regions in the frontal cortex mature.In the LiveScience article under "apathy," we get more detail about what thinking skills remain underdeveloped among teens:
The area of the brain associated with higher-level thinking, empathy, and guilt is underused by teenagers, reports a new study. When considering an action, the teenage medial prefrontal cortex, located in front of the brain, doesn't get as much action as adults.Poor decision making skills, an inability to consider consequences, absence of guilt, apathy about outcomes, and testosterone-fueled misbehaviors - honestly to describe it that way makes teenagers sound like sociopaths. Yet what parent of teens would dispute the description, at least on their kids' worse days?
Keep in mind these studies don't describe delinquent youth, they're studying average ones. That's why youth corrections differs from adult prison management, and why you hear so much talk about prioritizing "rehabilitation" instead of the "punishment culture" at the Texas Youth Commission. With the exception of true sociopaths, and they're a decided minority of kids, most TYC yough still have a chance to learn socially accepted behaviors, but nobody thinks they're learning them under Texas' current youth prison regime.