There is nothing abnormal about them. However, when anger is repressed for long periods of time, it comes out twice as strong as when it was repressed. It is well documented in the mental health field that repressed anger is a leading cause for depression. If an individual is not permitted to express himself, or does not permit himself to express his negative feelings, the feelings are turned on himself. Many suicides and homicides are a result of anger that was repressed over time.
Anger management is a learned skill.
Effective parenting and modeling by parents is the first course that children have at learning to express their anger. I have observed in my practice, if parents have trouble expressing their anger, so will their children. If children are taught to repress these feelings, they will have a harder time controlling them. In turn these children go to school and encounter situations that frustrate them and make them angry. Because they were not taught to effectively express anger, they act out.