Angelic images of smiling siblings make crowd-pleasing Facebook fodder, but the reality of life is decidedly less picture-perfect. According to research from University of Toronto, toddler-age siblings clash more than six times per hour; siblings under seven fight, on average, every 20 minutes. Fights that get physical can leave lasting physical and emotional scars. If sibling fighting is stealing the peace in your household, read on for relief.

Early Years 0-5

Research shows that conflict between young siblings is statistically normal. But regular bouts of biting, hitting, and kicking aren’t—parents should intervene when clashes between siblings becomes violent, according to guidelines from C.S. Mott Children’s Hospital in Ann Arbor, Michigan.

Though kids as young as three may be able to talk through minor disagreements that crop up during play (“I had it first!”), they’ll nearly always require guidance from a caregiver to navigate more heated exchanges and physical fights. Start by separating the scuffling sibs, with a statement such as, “we never hit.” Once children have calmed down, ask them to explain what happened, reassuring each child that they’ll get his or her turn to speak.

Statements that bridge the conflict to build connection can diffuse fights and guide kids toward resolution: “Jackson, I know Olivia is a good listener, so you can tell her why you didn’t like it when she pushed you.” Encouraging tots to use words to self-advocate (“I didn’t like it when you took all the blue Legos!”) can help prevent future fights from spiraling out of control.

Elementary Years 6-12

Bad news for parents of school-agers: According to a study led by David Finkelhor of the University of New Hampshire, “sibling attacks,” or acts of physical violence toward a sibling like shoving and punching, peak from ages six to 12. Over a third of children in the study experienced sibling violence in the past year. For about five percent, the violence was severe enough to leave a lasting mark like a bruise, a chipped tooth, or even a broken bone.

While violence between parents and children or between spouses is viewed as unacceptable, violence between siblings is often overlooked by parents as normal squabbling, says Finkelhor. In fact, repeated sibling attacks can have serious repercussions. In the study, children under age 10 who were repeatedly attacked by a sibling in the past year experienced signs of trauma, including sleep problems, depression, and fear of the dark. If sibling spats often get physical and seem one-sided, with one sibling most often playing the role of antagonist, seek help from your child’s pediatrician or a licensed counselor.

Teen Years

What’s mine is yours? Not so fast. According to Catherine Salmon of the University of Redlands, up to 95 percent of siblings say that personal property—a highly important part of children’s budding sense of identity—is a point of conflict between siblings. Though teens may be able to work through some property-related conflicts on their own, parents may not know if and when to intervene. “It can actually be a natural and healthy developmental process for siblings to work out conflicts on their own,” says Dr. Vanessa Roddenberry, licensed psychologist and founder of Breyta Psychological Services in Raleigh, North Carolina.

Parents who constantly step in risk invalidating teens’ emotions and communicating that fighting is an effective way to get caregivers’ attention and focus, Roddenberry notes. But when sibling fighting escalates to yelling or physical fighting, parents can help by separating siblings, putting the disagreement on pause while each party takes time to cool off and process their emotions separately. Once feelings have calmed, a kitchen-table meeting moderated by parents can help get teen siblings on the same page—and up the chances that next time, you won’t need to play referee.