Hi, I'm new to Mumsnet - but would desperately like some advice. I have lived with my partner for a year now, and he gets on great with my 11 year old son. I admit I am very over sensitive around my 11 year old and when his 2 girls come and stay and they niggle each other I get really annoyed. Why can't they just be nice to each other? He is my only child so I've never know what siblings are like with each other - they either play together really well or wind each other up. He gets all hurt too, and I take it so much to heart it becomes a drama! My partner says "this is how kids are" and that I'm over reacting. Please tell me this is normalwhen kids are together. My son obviously isn't used to it and looks so hurt, though I know he probably gives as good as he gets. Should Ijust tell my son to toughen up and ignore them! ?