Yeah right! You'll never end sibling rivalry! If somehow you come up with an equation (or potion), let us know! As far as we've seen, sibling rivalry lasts well into adulthood. There are different levels of course. There's the extreme, which can be just simply unhealthy. There's also the tit-for-tat, one-upping siblings do. This is just part of being a kid anyway! 

We can offer a few pointers though! 

1) Don't make everything a competition. 
              Do you find yourself saying things like "look how well your sister did!"? Or "When 
              your brother was your age he had straight As all year!"? Saying things like this really
              don't help your case. You may look at it as loving motivation, but chances are, your 
              kid doesn't see it that way. One kid is left feeling superior; while the other: inferior. 
2) Don't make a big deal out of every little argument they have.
              I know you've heard people say "choose your battles wisely". Maybe you even use that
              line, but really! Choose. Them. Wisely. You don't need to break up every argument 
              your kids have. Let them figure out compromise and forgiveness on their own
              sometimes. This will help them in future arguments! 
3) You don't pick the winner. 
              When you do end up separating a fight or splitting kids up because of an argument: 
              punish them equally. You shouldn't choose a "winner" of the fight. Both were fighting
              when it comes down to it. After all, the behavior we're punishing is the fighting; not
              "being wrong". 
4) Have special time with each child. 
              You want each child know he/she is individually special to you. Do your best to 
              have time with each child sharing love. A bonding moment. The older ones, especially,
              want assurance that they are still special to you even though there's a new little guy 
5) Why are they hitting? 
              Yes, some kids hit to communicate what they are feeling. They lack some ability to 
              verbalize what they feel/want. However, sometimes it can be a bit much. Provide 
              consequences related to the rule broken. No hitting. You hit. No more fighting video
              games for the week. If things get just downright aggressive and violent, maybe
              something else is going on. Do what you can manage first!