Why do 18-21 year olds act more like kids/teens than adults?

According to the law (at least in the US), you become a legal adult when you turn 18. According to the fact that biology and life doesn't work that way, you do not immediately lose all 'childish' tendencies the moment you turn eighteen. read more

Well, many 18–21 year olds act like kids/teens because they still are near their teen years. People don’t change because their age just went up by one number (in this case). They’re in between their teens (18 and 19 year olds are teenagers), but in between that ‘mature’ phase of being an adult. read more

Some adults are treated like 18-year-olds, and some aren't treated like 18 year olds. In my opinion, you are treated based on how you treat others, how you conduct yourself, and how truly mature you are with respect to those around you. I’ve supervised a 17-year-old that was so motivated that the sky was the limit. read more