Over the years, the subject of kids and bullying has heavily focused on peers and the psychological effect on the victims. But new research sheds light on the potentially negative mental health effects caused by another sort of bullying—sibling to sibling.  

The University of New Hampshire study found a link between sibling aggression and poor mental health in children and adolescents. In some cases, sibling aggression appears to be just as harmful to a child’s mental health as aggression coming from their peers. "Even kids who reported just one instance had more mental health distress," said Corinna Jenkins Tucker, PhD, lead author of the study and associate professor of family studies at UNH.  

To conduct the study, which appears in the July 2013 issue of the journal Pediatrics, researchers analyzed data from a national survey of 3,599 children ages 1 month through 17 years and looked at the effects of both physical assault and psychological aggression among siblings. Nearly one third of the children experienced at least one type of sibling victimization in the past year. Younger children (from 1 month to age 9) had greater mental health distress from mild sibling physical assault than adolescents (ages 10 to 17), but all ages were similarly negatively affected by psychological and property aggression.

The findings of the study are especially important since many parents quickly dismiss sibling fights as a part of growing up. When there's evidence that children's mental health is affected by various kinds of bullying, including that perpetrated by a sibling, parent intervention may at times be needed for what we think of as sibling rivalry or squabbling.