Sibel Nefa is not of Turkish origin. She is German. I know, because I know her personally. She dances a mixed Egyptian/American cabaret style.
Fatima Serin is of Turkish origin, but she dances Egyptian Raqs Sharqi. Why do you wonder about the fact, that there are more dancers dancing Egyptian than ones that dance Turkish? Egyptian is more artistic than Turkish, it has lot more movements and more difficult system and the Arabian belly dance music is more complex and interesting than the Turkish one. A short Turkish performance might be thrilling, but I could never watch Turkish style belly dancing for hours. Opposite to this, I cannot get enough of Egyptian style belly dance. You can compare Turkish style to Pop music and Egyptian style to Classical music. Of course at the end, it is a matter of taste
