Modeling of aggression by others is one way children learn to act aggressively. They have not seen nor been taught appropriate ways of coping when angry or frustrated. Conflict resolution has not been part of their education at home. Children have seen many hundreds of hours of violence in cartoons, video games, movies and on television by the time they are school age. Sometimes, children have a difficult time transitioning between what is real and what is fantasy. Others are in middle school before trial and error and teacher guidance has helped develop the skills needed to get along with others when problems occur. Some children are born with extra testosterone as a result of having an extra Y chromosome. Teenagers often channel this extra energy into the sports arena where being aggressive is more accepted.

Some children may become aggressive when frightened and may hit or throw things at others. This is the primitive fight or flight for survival instinct being manifested. To save face when challenged by others and to avoid embarrassment, some children will act out in order to show how tough they are. Children and adolescents with low blood sugar may experience irritability as they struggle to handle criticism, put downs or name calling. Some insults to the brain may cause a person to have underdeveloped emotional growth. These might include prematurity and maternal drug/alcohol use.

Aggressive behaviors can result from loud noises, fatigue, sleep deprivation and drug/alcohol use by the child or adolescent themselves. Low self-esteem can contribute to wanting to show others how tough they can be. Taking certain medications can make people feel fidgety, restless and irritable and, therefore, lowering their tolerance for annoying factors.