Well in my game as Poland, the first wife of my character was... a Bedouin. At least that's what her culture said, anyway, she was basically a courtier I found who had both the Genius and the Strong traits (though my character-at-the-time, my current one's father, was also Strong). So this resulted in the interesting fact that my two eldest son's are, in fact, Polish Catholics, with Polish names... who look like Muslims. The way things are going, one of them is very much going to be king, so that's going to be incredibly bizarre.
Oddly enough, his kids seem to be white, probably because he did marry European women. I guess there's a bit of a genetic factor there.