Brothers and sisters fighting with one another is just a part of growing up. But when that fighting moves into serious physical or psychological aggression, a new study confirms that sibling bullying can be just as traumatizing as bullying by schoolmates.

The study, published in the journal Pediatrics, finds that kids and teens exposed to aggressive rivalry from their siblings tend to report more depression, anxiety, and anger than other kids.

The researchers say their findings are important given that most anti-bullying campaigns have focused on peer aggression in school settings, and less on the bullying that can take place in the home.

The study focused on more than 3,500 children under the age of 17 with at least one sibling. All took part in long-term study called the National Survey of Children's Exposure to Violence.

The kids were interviewed by phone about bullying in the past year. (Adult caregivers answered on behalf of children under age 9.)

The researchers asked the children about physical aggression, psychological aggression, such as being scared by a sibling or being told they weren’t wanted around, as well as property aggression, such as stealing a possession or breaking a sibling's things on purpose.

They found that 32 per cent of children reported experiencing at least one form of aggression from a sibling. Younger children under the age of 10 reported more distress from physical bullying, while kids of all ages reported distress from the other forms of aggression.

Corinna Jenkins Tucker, an associate professor of family studies at University of New Hampshire and the lead author of the research, says parents and caregivers should take sibling aggression seriously because it can lead to the same serious mental health effects as peer bullying, even though many caregivers don’t take it seriously.

"If siblings hit each other, there's a much different reaction than if that happened between peers," she said in a statement.

"It's often dismissed, seen as something that's normal or harmless. Some parents even think it's beneficial, as good training for dealing with conflict and aggression in other relationships."

Parenting expert Alyson Schafer says there’s nothing unusual about sibling rivalry; siblings seem hard-wired to compete for their parents’ attention, and any two human beings trying to live in the same space are going to inevitably have some conflict.

But she says how parents respond to that conflict will determine whether kids end up becoming rivals and whether the conflict increases.

“What I look for in terms of assessing dysfunction is to ask: Do they ever get along? Do they always fight?” she told CTV’s Canada AM Monday.

“If you leave them alone and someone else is looking after them, are they still going at it the whole time you’re away? Because so much of what happens in sibling conflict is they’re trying to engage their parents. So if their parents aren’t there to referee and take sides, they tend to get along.”

The other thing she says she looks for is whether there are ever any unprompted gestures of goodwill.

“Those little acts of caring show you that behind the conflict, they still have a genuine love for one another,” Schafer said.

Parents concerned that their children’s fighting has moved into dangerous, aggressive territory should consider family counselling, Schafer advises.

“These are the things we’re trained in, to help families change those dynamics. There’s a lot that can be learned in a few counselling sessions,” she says.

As for everyday conflicts, Schafer advises never asking who started a fight or who had the coveted toy first, because taking sides will just add to the competition.

“Just say, if you can’t get along on the computer or wherever, you both lose the computer. If you can’t figure out how to share the pail, I’m taking it away until you can figure out how to share it.,” she says.

“So the consequences that befalls one, befalls the other.”