Sorry. I know it seems as if I post comments like this simply to be provocative, but the most common variable among young people who do stupid things is that they are stupid. Smart kids generally do not. Since we can't have honest conversations about intelligence in our society, we will probably end up penalizing the smart kids in a quixotic effort to protect the dumb ones from themselves, or penalizing young women (assuming that we still believe in that category) for the sake of dumb young men. There are far more dumb young men than dumb young women. This is left out of the age of majority debate.