Read a controversial article (at least in education circles) here. (Thanks to Wittingshire). The concept of adolescence being a relatively new phenomenon is something I first came across in homeschooling circles years ago.
My current experience with high school students (generally most turn 16 sometime during the school year) is that once they get a license there's a marked change in their maturity...especially if they have to hold a job to pay for gas and insurance. Suddenly they can relate, even if it's just remotely, to JeanValjean's struggle to sacrifice.
Which brings me to a related topic regarding the huge shift in the way 21st century students learn. But more on that later.