@reasoning logic,
Of course we don't care about these other people, in fact we hate them. We hate their very DNA.
We don't see them as our relatives because they aren't, unless you want to trace lineage back a few hundred generations. Besides, who knows if some of these people are even the same species as us?
Anyone who is not of Us, is of the Other, and the Other is always The Enemy (particularly if they have brown skin or slanted eyes).
Feel validated now?