yes, we're only as strong as the weakest link

Spock cannot divorce himself from all the things he is not; all the things he does not have.

On Earth (thus, among the Federation), he is the Vulcan. On Vulcan (thus, among his creators), he is the Human. The human, rather; they afford it no such capital distinction.

The people outside of him divide him more than his biology, inside, does. It is as much about his having a human mom, if not more, than it is about him having a human mother.

So Spock has no motherland, but Spock has a culture, to love in deeply personal, ritualized celebration.