Were you the winner or the loser in your sibling dynamic?
Many parents believe that sibling rivalry is healthy, natural and unavoidable. There are many causes of sibling rivalry (age, developmental stage, personality), but a main cause is the need for power, attention or protection from parents.
Children, as young as infants, find comfort in routine and predictability. The family dynamic is a source of familiarity and certainty, including the ways in which parents react to each child during sibling struggles.
When one sibling picks a fight, he usually knows what type of reaction it will trigger from the parents. In that moment, the aggressor is seeking the feeling that reaction provides — negative attention if he is punished or power that he succeeded as the dominator if the parents take a hands-off approach.