I think the best thing you can do is to stay out of it. Let them fight. Kids do grow up eventually and some who were bitter enemies at age 10 are best buddies at age 20. I say wait it out. I am a living example of a sibling enemy who became a sibling friend. I never got along with either of my sisters when we all lived at home. But when we grew up and established our own homes we all moved near each other and had kids together who play with each other and help each other just like sisters are supposed to do. Unfortunately, Mom died young and never really got to see how it all worked out. Trust me, things can and do change.

I have to disagree with your advice Virginia. It did work out for you guys, but I believe that sibling fighting can be very destructive while it is going on. My sister is two years older than me and she always thought she was too big to spend any time with me - even when we were already teenagers. Her avoidance of me really made me feel defective, like I wasn't worth anything. I felt this way even though I know my parents loved me. My parents never did anything about it. If my sister was mean to me, they'd tell me to just ignore her - that's all they ever said. I felt unprotected and abandoned by my parents because of this. They didn't really understand how hurt I was. Now that my sister and I are in our 40's nobody would ever know about our earlier history just from looking at us. We act very properly to each other at family gatherings and in social situations. However, we never became close and I, for one, never recovered from those two decades of unkind treatment. I think you should intervene and help kids learn to behave properly with each other.

I think there are lots of things parents can do to help siblings treat each other right. You can punish them when you see them being mean to each other. You can also reward them when you see them getting along. I've been using the CLeaR Method (Comment, Label, Reward) on my 2 boys and their relationship has really improved. Whenever they are getting along properly I say something like,"My you two are playing nicely." (That's my Comment)). Then I say, "That's very brotherly of you." (That's my Label.) Finally, I say something like, "I think you two deserve some special chocolates I set aside for good brothers." (That's my Reward). Well, these two guys just love chocolate treats and they have become the best of friends this past few months since I've been using this method. Of course, they are past the point of getting constant rewards for their mutual cooperation, but I still give them something once in awhile just "for old time's sake." They really deserve it. I really think you should try this approach (you can read how to do it in Mrs. Radcliffe's book Raise Your Kids without Raising Your Voice.)