Our childhood relationships with our siblings set the tone to varying degrees for our relationships in adulthood. Not every child has a close bond with his or her siblings; age differences and sex differences certainly play a part. Conflict between and among siblings is common. Older siblings often pick on younger brothers and sisters, and younger siblings may learn to use their status as the "littlest" to get their way.

For parents, the issue is how to distinguish between sibling rivalry, an unfortunate but relatively common and acceptable "family" behavior, and bullying, the sort of persistent aggression that causes troubling, long-term consequences.

The conclusions may change the way parents look at their bickering kids.

Bullying is a form of aggressive behavior in which someone intentionally and repeatedly causes another person injury or discomfort. Bullying can involve physical contact, words, or more subtle actions — taking schoolbooks, constant nudging, knocking, or online harassment. Typically, the person being bullied has trouble defending him or herself and does nothing to “cause” the bullying.

Children who are bullied and victimized during childhood and adolescence are more likely to develop mental health issues such as depression and anxiety that persist into adulthood.

The Effects of Sibling Aggression

A recent study looked at this question of bullying by siblings, and the conclusions may change the way parents view their bickering kids.

Many parents and professionals, the authors say, regard aggression among siblings as a benign and normal event which may even help to teach children how to fend for themselves among aggressive peers. But the researchers contend that sibling aggression is a form of violence that is no different in its mental health impact from similar peer-to-peer violence that is appropriately labeled as “bullying.”

The long-term effects of bullying have become all too clear in the aftermath of school shootings and the suicides of bullied children and teens. Schools and towns are making efforts to reduce bullying and victimization among peers. The researchers contend aggression among brothers and sisters needs to be addressed as well.

Many parents view aggression among siblings as a benign and normal event which may even help to teach children how to fend for themselves among aggressive peers.

The study’s authors asked children and teens aged 10 to 17 and parents of children from birth to age 9 to discuss their experiences with three types of sibling aggression: physical assault, property victimization and psychological aggression. They also asked parents of young children and older children to comment on the emotional impact of these acts. They compared the accounts to those by children and adolescents who experienced similar aggression perpetrated by peers.

The mental health of the children and adolescents was assessed by standardized questionnaires that report on anxiety, anger, and depression.

The study group of 3599 reflected an appropriately balanced ethnic population. Phone interviewers questioned the adolescents (10-17-year-olds) directly, and questioned the caregiver most knowledgeable about the children (0-9 years). They questioned them about their experiences over the last year. The study looked at both the type and number of incidents experienced over the past year and looked at the same types of incidents perpetrated by non-sibling peers.

Forms of Sibling Abuse

To investigate instances of sibling on sibling victimization, teens or parents were asked whether there were instances in which one sibling had:

  • Physically assaulted another without a weapon/object and without injury

  • Physically assaulted a sibling with a weapon/object and caused injury

  • Used force to take away something from a brother or sister that the child was carrying or wearing

  • Stolen something from a sibling and never given it back

  • Broken or ruined property of a sibling on purpose

  • Come to feel bad or scared because a sibling was calling him/her names, saying mean things, saying they didn’t want him around.

All types of sibling aggression, both mild and severe, were associated with significantly higher emotional distress symptom scores for bullied children and adolescents. The greater the number of types of sibling aggression a child or teen experienced, the greater the mental health distress. Sibling aggression was a unique and independent factor contributing to mental health problems regardless of experiences of peer aggression. This list of aggressive acts offers parents of siblings a sense of the sorts of issues to be on the lookout for.

Parents need to reconsider what they accept as normal conflict among their children and the sort of tone they are setting in their home.

According to the authors, “Although peer aggression is generally perceived as being more serious than sibling aggression, our analyses showed that sibling and peer physical and psychological aggression had independent effects on mental health and that the mental health of those experiencing sibling versus peer property and psychological aggression did not differ.

“Our study shows that sibling aggression is not benign for children and adolescents regardless of how severe or frequent. An implication of our work is that parents and pediatricians, and the public should treat sibling aggression as potentially harmful and not something to be dismissed as normal, minor or even beneficial.”

What Parents Can Do

The authors call for increased attention to sibling aggression by parents and those who teach and care for children and adolescents. They suggest including greater focus on sibling aggression and on strategies for mediation of sibling conflicts in popular parenting programs.

Parents need to reconsider what they accept as normal conflict among their children and the sort of tone they are setting in their home. Are children encouraged to help each other, or compete? If one child is consistently on the receiving end of aggressive behavior, parents need to step in and set clear standards for what is fair and what is acceptable behavior.

Siblings fight, and so these conflicts are easy to dismiss, but when one side always loses, or one child does not feel safe or protected, parents need to act. The whole family will benefit.

The study appears in Pediatrics.