"Families should be aware that the relationship between siblings, beyond encouraging it to be the best possible, will depend on the personality of each sibling," says Estrella Ferreira, a professor at the Faculty of Psychology at the Autonomous University of Barcelona (UAB). Each sibling has their own personality and interests, but doing things together that everyone enjoys can be encouraged, so as not to weaken the relationship. Maria Helena Tolosa, teacher, psychopedagogue, trainer, and author ofOur daily conflicts, agrees: "It's a bond that deserves respect, but they don't have to be friends. The relationship between siblings has a degree in itself, which is different from that of friends, although if both come together it's wonderful."

He's present every day. He's simply part of the family. For some, he's become unattainable, distant, and absent; for others, he can be a rival or even a hindrance that forces them to learn to share. A sibling is and always will be a sibling, but this figure loses all meaning when it lacks the most important thing: the bond. An affinity that ignores age variables because there can be a great difference but, at the same time, great cohesion; or there can be disinterest, rivalry, and competition, yet they can be only months apart. And when siblings aren't blood relatives? The realities of separated families (or other types) add new variables. What doesn't change—and never will—is that the bond between siblings depends, in and of itself, on many factors, and that, in these situations, the parents—who have a lot to say and do—become a pillar that tips the balance toward a context of conflict or resolution.