I feel this has been the case with my mum (my eldest sibling was the fav), my grandmothers and my 4 best friends' parents.
My DC is an only so I cannot comprehend what it's like having more. I'd love to think I could and I would be equal but I won't ever find out and cannot imagine loving anyone more than my one DC.
Is there anything in this? Are favourites inevitable?
It has done me considerable damage :(