I hadn't seen it coming that my children would fight all the time. I'm an only child, and of course, I had no idea this would be a constant feature of sibling relationships. In our house, you can always hear shouting, and someone always calls the other "Stop it!" You can imagine that, with four boys, they almost always play roughly, they're always hitting each other, and what starts as a game often ends in a huge drama. Are there siblings who calmly play chess all afternoon? Or do they make recipes with the hope of being the new Roca brothers? Well, not mine. Mine argue, get angry, and say all kinds of things to each other. And is this thing about siblings always like this? I asked, completely naively, people who have siblings. Yes, it's always like this.