Parents can play rough with their kids. They tend to if they value it. If they dont value it why would they let them play rough with others, who obviously care about their kids less than they do?

To be clear, im not saying it has to come from their parents. Just that it’s usually the dad powerbombing the kid on the bed and advocating for contact sports. This dynamic illustrated: https://imgur.io/8RZn2YF

never got in a fight with my parents, but there sure were plenty of shoving matches and occasional fists with the 8th graders on at me old schoolyard...