Laughing at a fool is whole hearted? How strange.
In most societies you become an adult at 18. You can vote, enter a legal contract, marry, drive an automobile (the most dangerous weapon on earth, just look at the statistics), be tried as an adult, take on debt, be drafted and sent to war, be sued in court. In other words, you become a full citizen of your society. It's only in the most degenerate of societies that these adults are considered a "kid". There are few things on this earth more pathetic than an adult with Peter Pan Syndrome, the inability to grow up.