I echo what annep says.....you feel closer to the ones you see more often. I have 5 grandchildren, but am closer to my daughter's 2 teenagers because, I practically brought them up. I don't see my older son's toddler and baby as much as I would like to, but I do see my younger son's toddler a lot, so there is that closeness with him. It's nothing to do with daughter's children or son's children...it's just who you get to see more. I don't feel any guilt, because I love them all, but due to circumstances/family dynamics, I see some more than others and therefore I feel "closer"to them.
23selba they are all your grandchildren. What do you mean you distance yourself from your son's daughters? My sons' babies are very, very close to the other grandparents and see them more because they do the nursery runs etc. I am ok with that, as I am much older and can't do as much. That's the way it goes. But to answer your main question, I don't feel any of them are mine !