We are speaking here not about the anger that drives people to shoot, or stab, or otherwise wreck havoc on their fellow humans. We mean instead that everyday sort of anger, annoyance and irritation that courses through the minds of perfectly normal people. It is necessary to know how we learn anger before we can take effective steps to dissolve or overcome our anger. The child identifies with the aggressive behavior of the parent unconsciously incorporates it in his psyche. Conditioning Pavlov's theory of conditioning can be applied to anger also.
Anger is a conditioned reflex.
As we grow up, we become conscious of our own personal agenda and whenever another human being or an outside situation interferes with this agenda, we feel a subtle nuisance. Each time we experience this nuisance or anger, we release adrenaline which is an anger provoking chemical. Several thousand nuisances later, we have created a cause and effect response to these minor nuisances, like traffic jams, etc. Once this condition response is established, we believe that only aggressive behavior can achieve the desired result for e.g., the parent might give in to the tantrums of the child by agreeing to what the child wants, but the net effect is that the child has been rewarded for throwing a tantrum. As a result, he feels that to control a situation he needs to be aggressive.