A adult is a person poisoned by experience. The poison makes you capable to navigate the world easier, but the poison that is knowledge also inhibits and limits you. If you know more about the world or the future, you are less likely to have children. The more knowledge you have the more it limits your ability to move of the rails, do novel scientific discovery, etc. An adult is thus the most information poisoned person in the room, all others are in degrees lesser adult thsn him or her.