Social Learning Theory
This theory, made famous by Albert Bandura, states that social behavior (any type of behavior that we display socially) is learned primarily by observing and imitating the actions of others. The social behavior is also influenced, according to this theory, by being rewarded and/or punished for these actions. For example, if a child sees his older brother bring home a good report card and he gets a great reward for it, the child may observe this, see the older brother get rewarded, and then learn that having a good report card will get rewarded so he should do it too.