So often we view anger negatively but it is a natural emotion. It is important to understand that anger is a secondary emotion, usually following fear, disappointment, or extreme sadness. Anger itself is not bad unless it hurts us or others. It's easy for children to understand how getting to angry can hurt other people but what they fail to identify is how they allow anger to hurt them self.
Consider the anger illusion. The anger illusion is the belief that we are winning when we get angry with someone that is trying to make us upset. In the example of sibling rivalry, usually one child is poking fun at another and enjoying their. Their entire goal is make their brother or sister upset. They want to get a "rise" out of them. The other child, not wanting to play the game, gets angry and flies off the handle by yelling, running away, or sometimes escalating the situation to a physical fight. While they may feel like they're winning, they've really fallen for the trap. They've taken the bait and now their hooked. It's likely that their escalated response will actually get them in trouble, not the sibling who started it.
It's important to teach your kids about the anger illusion and remind them that if someone is picking on them and trying to make them upset, it's simply a game. The way to win is to stay calm, be kind, and be strong on the inside. The other person will not have any fun if they don't get angry and will soon move on to something or someone else. People that are resilient aren't easily phased by how others treat them and those who are focused on loving, keep their eye and the goal, treating everyone like friends, even their enemies.