Parenting - sibling rivalry/fighting?

I think it is mean and disrespectful. I would have been punished if I had acted like that to my brothers/sisters. You should be stepping in and taking away privileges. How are children to learn respect if they are not taught at home. Family is sacred and no one should ever be made to "lived through it" when it can and should be stopped. You might want to check into the dangers of some of this "harmless" actions such at "twisting" and wedgies which can leave permanent damage.