Anger is a natural emotion. It is the tool you have which allows you to say, "No, thank you." It does not have to be abusive, and it never has to be damaging to another.
When children are allowed to express their anger, they bring a very healthy attitude about it to their adult years, and therefore usually move through their anger very quickly.
Children who are made to feel that their anger is not okay—that it is wrong to express it, and, in fact, that they shouldn't even experience it—will have a difficult time appropriately dealing with their anger as adults.
Anger that is continually repressed becomes rage, a very unnatural emotion.
People have killed because of rage. Wars have started, nations have fallen.