Ask Another Mother: How can I get my kids to stop fighting?

There are some parenting dilemmas you can't solve on your own, right? Because it takes a village to raise a child. So if you have an issue you need some help with, drop us a line at and we will put it out to the iVillage community.
Dear iVillagers,
I know it's normal for siblings to fight but my children are out of control.
It's like they hate each other. They actually physically attack each other on a daily basis and I'm just sick of it. Why can't they just get along?
When I was little my sisters and I had some massive fights. One minute we'd be playing a game and the next we were pulling each other's hair, screaming and crying and hating each other. I never wanted my kids to be like this. Where did they learn to hit and kick and yell and scream at each other?
And my youngest is the worst. She taunts her two older brothers and if they upset her she just attacks them. She's 4. They are 9 and 5. I've told them that because they are bigger than her they aren't allowed to fight back, they have to call me, but that doesn't always work because she bites them too. Are they just meant to take it?

Not her actual children although apparently she has several shots she could supply

I read an article that totally freaked me out about how sibling bullying is just as bad as bullying from peers. Being picked on by brothers and sisters can cause anxiety and depression. And it does, because I remember how sad and lonely I felt when my sister's ganged up on me and left me out. They'd tease me often and I'd throw things at them in a rage and usually be the one to get into trouble.

It's so strange because we're best friends now.

Am I over-reacting?

This study also said that parents shouldn't turn a blind eye and write it off as normal. But then I read a parenting book that advised me not to intervene every time my children fight and disagree because they need to learn how to deal with conflict themselves. I don't want to do that. I want to teach them not to be so cruel to each other. I want them to be able to share and help each other, to protect each other and love and care about each other.

Is it normal for kids to fight? Should I just leave them to it? Should I intervene?