>Finally, do you really think that humans are not inclined to treat their
>immediate kin preferentially? In other words, the only reason that people
>love their children more than they love total strangers is because culture
>has taught them to?
These two explanations are hardly the only options. In my experience,
parents of adopted children show just as much devotion to their
children as other parents. That is not because they are biologically
programmed to treat their adopted children preferentially or because
it is a cultural norm, but because they choose to become parents and
live in an intimate social relationship with their children.
I am not a parent, but I have special affection for my own dog
compared to many other similar creatures. I assume that even the most
enthusiastic sociobiologist will not attempt an explanation in terms
of kinship in this case.