For children, receiving attention is a sign that they belong. Most children believe if they cannot get attention, they do not belong. Children generally repeat behavior that gets their parents' attention. If you notice cooperative behaviors, children are likely to repeat them. If you notice irritating behaviors, children are likely to repeat those as well.
Many parents have trouble seeing good behavior.
Sometimes that is because there is little good behavior to be seen. More often it is because parents aren't used to looking for good behavior. Once you get used to noticing cooperative behavior you will probably be surprised how much there is. List ten things you would like your child to do. Spend five minutes, twice a day, looking for those behaviors.