If someone suggested that having anything less than the widest possible gene-pool was a good idea, we would laugh. Yet, if someone suggests limiting immigration and thus having a sub-optimal cultural pool, we are supposed to politely explain to them and not treat them with the contempt they really deserve. Xenophobia is not an idea, and the only unnatural concept is believing that immigration is somehow new when it isn't. Any examples of racial tension are usually always started by the ethnic majority, not the incoming population; I like to see anyone prove otherwise. My whole point is this. If anyone spouts an idea that doesn't match what we already know of the world, they have to prove it. Half-baked ideas deserve contempt, not sympathetic explanations and immigration control is the biggest half-baked idea of all.