Thanks to Terra Nova for their article discussing the prevalence of gender-bending in online RPGs
. According to statistics worked out in the piece, "[in EverQuest], every 1 out of 2 or 3 female characters is being played by a male player, while every 1 out of 100 male characters is being played by a female player."
The article also notes that, according to the statistics, "The demographic that is most likely to gender-bend is not male teenagers, but men over the age of 25"
, suggesting one reason for this might be that "younger male players are probably less secure about their own gender identity."