Why a child resorts to anger and/or aggression?

To respond effectively to aggression and anger issues in children it is imperative to understand the underlying reasons. The incidence of anger in a child is polymorphic and could have its root in a number of emotional conditions, medical issues, family environment, and life circumstances.

Sometimes, in young children aggressive, aggressiveness is a defense mechanism to deal with insecurity, failure, low self-esteem, bullying, and loneliness, though on the face of it, it may seem to have been triggered by a certain situation. Children often express anger and aggression when they want you to listen to something that they aren’t able to communicate in words.

There could be many reasons that lead to a child being angry and aggressive.

Learning issues: Kids who have problems with learning and coping in school could develop a low self-esteem and feel threatened. Children with cognitive or communication issues may display aggression as a coping mechanism to deal with their failure. They do so because they are not sure how to better with their anxiety or frustration.
Family environment: Children are quick learners. Many a time the family environment is hostile and disturbing. When the child witnesses one or both parents yelling, abusing and threatening each other, they acquire the behavior over time and model themselves after the parent/s without even realizing it.
Media exposure: In today’s digital world, we can do little to stop our children being exposed to in-the-face media. A study at the University of Washington in Seattle found that for every hour of TV 4-year-olds watched daily, their risk of becoming bullies at ages 6 to 11 increased by 6% to 9%. In another study, from the University of Michigan’s Institute for Social Research in Ann Arbor, girls ages 6 to 10 who often watched shows with aggressive protagonists were found to be more likely to develop into angry adults.[1] Children are also exposed to violent video and computer games that gradually increase their hostile behavior and aggression.
Sibling rivalry: As parents we often commit the classic mistake of comparing and pitting our children against each other, comparing them in front of guests and relatives and offering unequal affection. This leads to erosion of self-esteem and self-worth of the child.
Anger as a negotiating tool: Many children use anger and aggression as a tool for achieving a personal agenda. They resort to anger to negotiate their terms and get the parents to give in to demands that they know are not justified. If the child is able to manipulate the parent even once using anger as a tool, he will in all likelihood use it over and over again.
Bullying, failure and sense of loss: A child could be undergoing an array of emotions without being able to express them verbally. He could be facing bullying at school, failed to be chosen in the school cricket tea, dealing with the loss of a grandparent and more. The child considers accepting failure and sadness are a mark of weakness, instead resorts to hostility, anger, and aggression.