[mikeash]

Race and "continental origin" are only vaguely related.

For example: what race is the current President of the United States? Most would say "black" (or "African American" if they're trying to be politically correct). And yet his ancestry is half European.

This is hardly an isolated example. The average African American has about one quarter European ancestry. About 10% of African Americans have a majority European ancestry.

Yes, you can use genetics to divide up humans into related groups. But those groups will not match with how we divide up races.