Women can be men. We are now capable of transforming ourselves into almost anything we want within the bounds of our species. We have even started to push at some biological barriers. The rampant use of plastic surgery by celebrities is so extreme it has created an inhuman human ideal. Plastic surgery also allows us to recapture our youth.
Bodybuilders have more muscular mass than is naturally possible thanks to anabolic steroids.
Truly dramatic changes, like the inhuman avatars I observed in Golden Compass are not yet possible in the physical world. But in time the cosmetic applications of genetic engineering may result in our becoming that malleable. The difference between enacting personal change in the real world and in a MUD is the ease with which transformations can be performed. To switch sexes in a MUD all someone has to do is spend a couple of minutes altering their personal description. To switch sexes in the real world requires thousands of dollars and several months of painful operations and hormone therapy.