Re: Why so few people come from the colonies...?
Not just ethnic groups, but others too, like those who leave to escape religious persecution. For instance, a planet of members from the W*stb*r* B*pt*st Ch*rch who visit other worlds to hold signs at funerals for disaster victims. In which case, we just nuke the site from orbit. It's the only way to be sure.
Curly: Moe, Larry, the cheese! Moe, Larry, the cheese! (Horses Collars, 1935)