How come you love them just because they're yours?

I’m looking at the pictures of my new grandson and I just love him. I haven’t seen him or held him yet. Arguably, he’s no better or worse than any other baby and not even any more beautiful. But he’s my son’s baby and i just want to hold him. Obviously this is also true of your very own babies. Is it instinctual, evolutionary, narcissistic or what?