There have apparently at least a few white South Africans who have checked that box and caused much grief in their local HRs.
I believe that a lot of the mystery that surrounds the history of the current occupant of the Withe House is due to his unwillingness to reveal just how he had gamed the affirmative action system. When he wanted special treatment as a foreign student, his country of origin was Kenya, or, perhaps, Indonesia. When he wanted to be president, he was born in Hawaii.