[philwelch]

Mixing doesn't create diversity, it eliminates it as people gravitate towards a common basis of law and culture. Entire languages are either extinct or spoken only by small fringe minorities thanks to cultures mixing together in the same country (or even the same nation-state, or previous membership in the same nation-state as in the case of Eire).

And it turns out that having separate countries protects cultural diversity too. What's the law in a country shared between people who have polygamous traditions and people who have a tradition where only monogamy is allowed?