You know the only people who are always sure about the proper way to raise children? Those who've never had any.
Parents are not interested in justice, they're interested in peace and quiet.
No matter how calmly you try to referee, parenting will eventually produce bizarre behavior, and I'm not talking about the kids. Their behavior is always normal.
My childhood should have taught me lessons for my own fatherhood, but it didn't because parenting can only be learned by people who have no children.