Met my DSis and DM food in my lunch break today.
There were a few words when DM told DS she was annoyed re something DS had done. I backed DSis that DM was being unreasonable.
Anyway when DM was in the loo DSis suddenly announced 'if she wasn't my mother I'd have nothing to do with her. I get nothing from this relationship'.
I was totally  because they have their moments but I didn't realise she felt like that about mum.
I do get annoyed with my DM but I love her and I enjoy her company most of the time!
As a parent I'd be devastated if my DSis grew up and said something like that about me. 
Is it ok to feel like this about a parent? I'm talking 'normal' upbringings, (in my case that means not a lot of money but never wanted for anything, ingrained work ethic, no abuse from either parent etc)
Am I unreasonable to think my sister is out of line?