A new study published this week in the journal Pediatrics shows that the aggression so commonly seen among siblings can negatively impact the mental health of children and adolescents.

Researchers from the University of New Hampshire (UNH) looked at sibling aggression data from the UNH Crimes Against Children Research Center’s National Survey of Children’s Exposure to Violence (NatSCEV), which samples 3,599 children with ages ranging from one month old to 17 years old. They found that 32% of children surveyed report at least one type of sibling bullying over the past year, which includes physical violence, psychological abuse, or property aggression (breaking or stealing things). Upon further analysis, the mental health of those children was found not to differ from children suffering from bullying by peers.

“Even kids who reported just one instance had more mental health distress,” said Corinna Jenkins Tucker, lead author of the study and an associate professor of family studies at UNH. “Our study shows that sibling aggression is not benign for children and adolescents, regardless of how severe or frequent.”

Though bullying by peers was previously assumed to affect children more seriously, Tucker and her colleagues concluded that sibling bullying can affect children just as much as peer aggression. The same mental health effects caused by peer bullying were found to result from sibling bullying. The study’s authors have suggested that pediatricians take sibling bullying more seriously, confronting parents with this information and providing them with approaches to mediate sibling conflicts.