I read a report on another piece of research a year or two ago. It said that, during puberty and the teens, the frontal lobe is developing so rapidly that other parts of the brain actually take over some of its work, and some of its functions are considerably diminished for a few years. One of the functions of the frontal lobe is that it is the seat of empathy. The evidence suggested that this is the reason for the self-obsession and selfishness which are often a component of the teenage years. Interesting stuff.