Let's bring this back to America. The whole point of America is there is no established population. America is who is here. We aren't theory, we're the facts on the ground -- the ultimate experiment in pragmatism. We aren't like France where unless you are "French" you can live there for seven generations and you're still not French. There is no American ethnicity. We are the mixed breeds of the world. A person who comes to America is just as American as a ninth generation Daughter of the American Revolution.
Conservative xenophobia traces back to the original sin of the right: they never understood America. They think it's a white, Christian nation and the rest of us are here by their sufferance and we should be grateful for what scraps we get. They are exactly wrong. America is a nation of immigrants. There is no ethnic hierarchy here except the delusional one that particular racists imagine.
America is sanctuary from all the nationalist and ethnic idiocy of the rest of the world. It is fundamentally post-ethnic. The slack-jawed rubes who think they're special because they share the race and religion of the Founders are in for one helluva shock the next century or so.