It can happen. Look at Michael Jackson, he's black AND white.
Some funky spunk action going on there for sure...
Doctors say the phenomenon is so rare, that there are no statistics to illustrate the probability of it happening. @ 1million to 1.
"Even non-identical twins aren't that common. Non-identical twins from mixed parents, of different races, less common still. To have two eggs fertilized and come out two different colors, less common still...."
http://www.google.com/search?sourcei...nd+white+twins