My boys had a friend who lived up the block who had a baby brother. Whenever they visited Jason they sat in the same room with his baby brother. The mother was on the phone. Finally they said to my wife, “I think she wants us to babysit Jason’s younger brother.”
“You don’t have to go there if you don’t want,” was my wife’s reply. Kids soon catch on to ulterior motives, and it may be that they have to learn the art of giving, but every day? So they had fun skateboarding, far from Jason’s house. I tried, with my wife, to give them a balanced upbringing.
They learn best from example, so I was ready for that, but I never verbalized it. I just didn’t think of explaining it. Instinct comes into play for human parents as for Robins who feed their adolescent offspring on the run.
Civilization 