Squabbling's just a normal part of having a brother or sister, right? Actually, when sibs get physical, it can be more harmful than we realize, according to a new study in the journal Child Abuse and Neglect  -- even causing anxiety, anger, and depression when it happens five or more times a year. Kids ages 6 to 9 were the most common victims in the study, with older kids usually  -- but not always  -- the perps.

The researchers didn't look at how bad brawls have to be to trigger these symptoms (it may vary from kid to kid), but they stress that children get just as upset as we do when punched, pinched, or slapped. To curb spats, from bickering to belting, follow this advice from John Caffaro, Ph.D., author of Sibling Abuse Trauma:

Give your kids positive attention. "Fifteen minutes of one-on-one time a day with a child can significantly reduce aggressive behavior," says Caffaro.

Teach them to express their feelings verbally. Help them find words for their emotions so they don't resort to names or abuse.

Hold them equally responsible. "Parents often jump in and protect one child  -- usually the younger," says Caffaro. "This can escalate the conflict." Instead, tell kids they'll have to find a way to compromise on their own, without whacking.