[tetromino_]

This may be the correct attitude towards school-age kids, but is plainly wrong when dealing with toddlers. For one thing, very young children are usually unable to empathize. So they are unable to understand why it's bad to seize their cousin's toy, they are unable to understand why it's bad to leave a mess for someone else to clean up - they can be taught a set of rules of behavior, but they won't really get the principle underlying those rules until their brain grows more and develops the ability to imagine themselves in other people's shoes.