At least in the American culture, girls are trained much more than boys to regard sex as icky, even in its vanilla form, let alone anything kinky! The shame response as regards our mutual interest is all but hardwired into most Americans, myself included, at least to a limited degree

. Based on several studies I have read, and a lot of wild surmise, I think that it is, on average, easier for men, at least among Americans, to overcome that response and actually go public with thier thoughts.
The studies on the gender gap are just fascinating. From differences in predisposition towards 'boldness,' which probably helps to explain this gap, to apparently natural sexual predispositions as regards the S&M scene. This is not to imply that either I or the scientists who conduct these studies mean that every woman is a submissive and every man is a dominant, but the averages do trend in the direction of dominant sexual fantasies for males and submissive for females.
Sorry if that was a bit incoherent, but I am very tired, and the thoughts are deep. Probably post again after I sleep a bit.