Every parent has a favorite child. Every pet owner has a favorite pet. We love them all and they're all special, but there's one that is easier or has a better connection, or whatever it may be.
I don't know why it is so SHOCKING to people that this mom is admitting to having a favorite.
Of course they always have to bring up the people who [very tragically] can't have their own family.
Teach your non-favorites to realize they suck and to be better and try to become the best... that's how life works, isn't it?