At age 13, kids who acted “old for their age” — by making out with other girls/boys, engaging in deviant behavior like sneaking into a movie, and also hanging out with attractive people — were deemed to be more popular by their friends compared with other kids. (People who are attractive, or who try to strive to be more attractive by wearing makeup, etc., may be perceived as more mature, the researchers said.) These cool kids also cared more about being popular than did other teens.

But by age 22, these behaviors were linked with declines in popularity, and the former cool kids were perceived as being less competent at managing their relationships or getting along with friends.

The cool kids were also at greater risk for criminal activity and substance use problemsat age 21 to 23. In fact, acting old for your age in middle school was a better predictor of drug problems in adulthood than was drug use in middle school.