As most of you know, I have a big interest in genetics. Here is a story I found interesting!
German bi-racial twins are a different skin color! Is there a German version of Maury out there?
UPDATE: After thinking about this some more, this is NOT that rare of an occurrence. Here are twins of a different color in England, Australia, Holland (the dutch babies have 2 different fathers) and I am sure if I had another 2 hours to spare, I could find even more examples. Here are even more in Germany from 2006! Here is a video of the British twins.
Different skin toned twins born to biracial parents are simply a matter of genetics. Remember, fraternal twins are not any more related than brothers and sisters. The way this happens is not rocket science. First the fraternal twin part. Most women have some sort of genetic predisposition to release 2 or more eggs at one time OR they are on fertilization drugs that encourage egg release. 2 eggs fertilized by 2 different sperm.
If the parents are of 2 different racial backgrounds, you can see how easily this occrance might happen. In fact, skin color itself is not totally understand because it is polygenic (controlled by more than one gene) Mixed race parents have genes for both dark and light skin tones. When sex cells divide, called meiosis, the number of genes a sex cell has is cut in half! (think about it-the cells only need half so they can fuse with the "other half" -either sperm or egg) If one of those sex cells have genes for only light or only dark, you have a differernt colored child!
What makes this uncommon is the twin part. There would need to be four of these rare single-race sperm and egg cells, and then the "black" and "white" eggs have to be fertilized by the sperm cell of the same "color." (info came from this website)
There it is in a nutshell. Biology 101!