Notes from an emergency room doctor: “Shut up! Shut up!” he shouted.

“You shut up,” the other yelled back even louder.

They are closer than friends, but not friends.

“You’re not using it,” one says insistently.

“I don’t care. It’s mine. I want it back,” the other retorts.

They are similar, yet vastly dissimilar.

“He threw it at me on purpose,” one cries, holding his hand to his bloodied brow.

“He started it,” is the non-apologetic answer.

They commit the most hateful acts against each other, and still forgive. Who are these people? They are your sons and daughters, your brothers and sisters. They are siblings.

How is it that siblings – children sharing the same parents, growing up in the same home, participating in many of the same life experiences – can grow up to be vastly different? Parents think it is their input that is instrumental in the development of their children. They struggle to nurture, to educate, to discipline. But when they have several children, rarely are they very much alike. More often siblings are distinctly different from one another in demeanor, intelligence, and interests. The answer to this conundrum is that while children may have the same parents, they have different brothers or sisters. Their interaction with their siblings may be the more significant factor in creating their differences, their uniqueness.

Although we may decry sibling rivalry and squabbling, some degree of that physical and mental bashing – short of the extremes that create mass murderers or leave irreparable scars for shrinks to cure – may be the developmental catalyst that makes each sibling what they are in life, what makes them “somebody.” For instance, studies have shown that children who deliver the most teasing, insults, and other negative behaviors to their siblings develop higher self esteem. On the other hand, those on the receiving end may become more disciplined, thicker skinned, and steadfast in their goals.

Though most parents exert great efforts to distribute love and attention equally to their children, most children perceive that when it comes to their brother or sister, “Mom loves them more.” That’s because it is impossible for a parent to display the same kind of love toward a 5 year old, for instance, as toward a 9 year old. Each requires a different kind of attention. But from each child’s perspective, the other is getting a better deal, and is loved more. No parental explanation can change that perception.

Eighty percent of us have siblings. The relationships we have with them endure after the death of parents, outlast marriages, and flourish despite conflicts that would destroy ordinary friendships. As a sibling, you’ll remember the battles with your brother or sister as “their fault.” But you will likely still forgive them and love them, even though Mom loved them best.