Q: Should I punish my boys—ages 12, 9, and 8—when they speak very meanly to one another? They say things like "You're stupid" and "I hate you." Other than this, they are very good and do well in school. Their teachers say they are exceptionally kind and respectful to other students.

A: If this were part of a broader pattern of misbehavior that included belligerence toward adults, demands for instant gratification and problems at school, I'd recommend action. In the absence of other problems, however, I'd let this one go.

When parents get involved in sibling conflict, they almost always identify one child as villain and the other as victim. The villain receives punishment, which increases his determination to "get back" at the victim. The victim is rewarded for victim behavior, which causes him to look for further opportunities to lure his sibling into a clash. In other words, parent involvement in sibling conflict almost always makes the problem worse.

At most, I would tell the boys that when their squabbling causes your head to throb, you will sit them in chairs in separate rooms for half an hour, during which time they would do well to contemplate how they can help bring about world peace.