About.com said:A mixed-race British mom gave birth to twins recently - one of each.
No, not a boy and a girl. Two girls - one black, the other white.
[...]
While very rare, the phenomenon is not unknown, though it does entail a very particular combination of circumstances at the moment of conception. First, both parents must be of mixed race. Second, the twins must be fraternal (each conceived from a separate egg fertilized by separate sperm) as opposed to identical (both conceived from a single egg and sperm). Third, each sperm and egg must carry the genes for a particular skin color (i.e., black/black or white/white).
The odds against it are indeed a million to one.
http://urbanlegends.about.com/library/bl_black_and_white_twins.htm
Pretty interesting happening I think.