It's not so much keeping the genetics pure (there aren't too many pure bred Americans), it's keeping the western ideology of freedom pure that is important.
No sharia ghettos.
exactly.
I do not know if it is biology, sociology or politics that keeps the Third World the Third World. However, I for one have always believed that Third Worlders are warm, rich and deep. They have invented everything and defeated the Nazi’s in WWII. They have proper relations with their families and are kind to their dogs. Now all that being acknowledged they can go home and be just as great.