Identifying people according to ethnicity is the problem, not the solution. No-one can choose where they came from (ethnicity) but everyone can choose where they want to go, to what or which sovereign entity they wish to give their allegiance,. But it requires that soveriegn entity has belief in, and therefore is prepared to enforce, its cultural norms so that those who wish to be part of that entity are assimilated by their own choice into thge prevailing norm. In short, multiculturalism is the problem, not multi-ethnicity.