The basics of social behavior come from the brain’s emotional system, which is an important contributor to empathy and morality from infancy through adulthood. Babies often cry when they hear another baby crying, because knowing that another person is unhappy makes them feel bad.
Even rats will work to help another rat who seems to be in distress. So some precursors of social skills are probably built into the brain, but experience also influences how well children understand and respond to the needs of other people.
Initiating joint attention to an object is one of the earliest indications of social skills. Babies who frequently point out interesting things to other people at nine or ten months are more likely to be rated as socially competent at two and a half years. By their first birthday, babies already like characters who help others better than those who hinder. True empathy, the ability to appreciate and talk about other people’s feelings, develops by age five.