That\'s a pretty broad generalization, Venge... Some people do RP their gender, although I don\'t know how they do it. I don\'t know how to get women, let alone act like one... I think its probably more common than most people would think, there\'s a certain stigma in RPGs about cross-gender roleplaying, so some people might keep it secret.
Although, it might be interesting to have gender bonuses; I know I\'ve seen them before, but I can\'t remember in what game. Although, a) I can\'t think of how they would ever be fun, I think more than anything it would restrict RP in the game by forcing people who want to be successful into specific genders. b) It would be nigh-impossible
not to be attacked by at least someone if it was implemented, but that\'s not such a big deal, really; unless of course they boycotted you...
c) There\'s always the magic words, \"I didn\'t do it\", or, \"Its Talad\'s fault!\"

Anyway, partly as Moogie said, there\'s little that one sex can do that the other can\'t (other than the physical attributes that actually seperate the sexes). There are some minor innate differances (innate strength in males, innate emotional and mental capacties in females), but these can be overcomed.
Ylians are the generic, \"do-anything\", race, correct? If so, one solution might be making the Ylian sexes identical, while making gender differences in the other races. This might lessen any outcry against the feature being implemented.