Sibling Aggression and Its Damage

Jump on baby's tummyWhen I was an infant, my sister jumped up and down on my stomach in my crib trying to kill me, she told me years later. I don’t remember that, of course. When I was a toddler I idolized her; my big sister could do everything. Before I started kindergarten I began to fear her bullying and to realize she wasn’t on my side. She would humiliate me by teasing, hitting, hurtful tickling, and addressing me as Stupid and other derogatory names. Coming home from grammar school, I’d listen at the front door for where she was. If she was to the right, I’d go left. If she was to the left, I’d go right.


An article in the New York Times, When the Bully Is a Sibling, by Anahad O’Connor validated some of the feelings I had as a child. According to a new study of 3,600, children and teenagers attacked, threatened or intimidated by a sibling have increased depression, anger and anxiety. Researchers conducted interviews with children and their parents, looking at physical assaults, destroying or stealing property, and threats, name-calling and other forms of psychological intimidation. “They also measured the same types of behaviors perpetrated by peers outside the home… in order to tease out the specific roll of sibling violence,” wrote O’Connor.


This subject has rarely been studied because fighting among siblings has been seen as beneficial or unimportant. But “chronic physical and verbal abuse is particularly damaging when it is directed at one sibling.”


Corinna Jenkins Tucker, lead author of the study published in the journal Pediatrics, said, “Behaviors among siblings that cross the line into abuse deserve more recognition. The programs… aimed at stopping bullying and violence in schools and other settings should include a focus on sibling relationships.”


Clinical psychologist John V. Caffaro said, “While normal rivalries with siblings can encourage healthy competition, the line between healthy relations and abuse is crossed when one child is consistently the victim of another and the aggression is intended to cause harm and humiliation… It can erode their sense of identity and their self-esteem.”


Parents who don’t intervene, play favorites, or give their children labels that show division inadvertently encourage conflict. According to Catherine Bradshaw, an expert on bullying, “Parents [think] their kids can fight it out or that a little bit of victimization might not be so bad, but these findings suggest the threshold is pretty low. It’s not just the rough stuff you have to keep an eye out for.”  


Was my sister put in a position where it was inevitable she’d hate a sibling—or was she somehow the source of her own hostility? She seemed dissatisfied a lot and had severe mood swings. Her envy, angst, and investment in the dramatic suggest she was type 4, the Romantic in the Enneagram system. Her blaming and her perception that threats were bigger than they really were suggest type 6, the Questioner. I am a conflict-averse 5, the Observer.



Years ago, my mother and I lived in the same town. She was in her late 70’s and had the beginnings of Alzheimer’s. One night, my sister, who lived over an hour away, came with moving vans and took our mother and her houseful of belongings to live with her. I can only imagine the planning and intrigue that went into pulling this off and keeping it a secret from me.

The next day I tried to reach my mother about getting together as we had planned and was distressed when she didn’t answer my phone calls. When I discovered what had happened, I felt baffled—and angry about the plotting behind my back. This episode was the final blow. I hope my sister is healthy and happy, but I no longer see her or talk to her.


I’m glad this topic is getting attention. Ms. Tucker’s research is sure to save some sibling relationships.


Please read my blog on Death Cafes in Psychology Today.


Visit for Famous Enneagram Types and to check out my books (including “The Enneagram of Death”), CD, cartoons, and essays.


3 Responses to “Sibling Aggression and Its Damage”

  1. Juie Says:

    In many ways siblings spend more time with each other than with their parents. Parents are at work most of the time and busy. Siblings become one’s first experience with ‘peers’. They are effectively your experience of peer group. So they represent and come before all of the peers to come. That is why what they say has such a powerful effect.

  2. Thom Says:

    How can I get across to my three year old the seriousness of attacking my infant. I caught the three year old hitting the infant when my back was turned. Realizing it might be an issue before hand it had been fully duscussed and thuroughly explained to the three year old but he attacked the baby anyway and I fear for the infants safety. The three year old could gavevserioysly hurt the infant. I kniw corporal punushment us frowned upon but the level of seriousness here is through the roof. What do I do? I cant leave the three year old locked in his room all the time. But at the same time I dont trust him.

    • Elizabeth Wagele Says:

      What a problem. It’s bad for both the baby and the three year old for this to continue.
      Please visit an expert in child behavior to find a solution, a professional who has dealt with
      this problem with other families. Please do something to change the pattern.
      – Elizabeth

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