Because sometimes little brothers and sisters can be a pain, right?😂
Yes its normal at the very start when a new sibling comes along but it needs to be dealt with quickly.
Kids need to learn not everything is about them and they're not the only ones in the house or world.
I remember playing hide and seek with my brother when we were about 10 or 11. And I went to go hide in my room and he cheated. And so I ran in and I shut the door but I got his finger slammed in the door and he started banging on it for me to open it. So I opened it and he hit me so I shut it again and then opened it and punched him dead Square in the face. We wernt on speaking terms for a few days lol. I think it's pretty normal. Kids are going to fight and they're going to be mad at each other but they always have each other's backs when it comes to other people messing with them.