Well, for starters, gender itself doesn't make a lot of sense. I mean : really all the configurations exist, between gender swapping with or without attraction to the same or other sex, between gay, straight, and bi cross-dressers, the whole range of attitudes and preferences. Then, "taking on a genre" itself is not an univocal notion : which aspect of life, what activity or attitude, is gendered and how, in what context what "role" is taken for how long, in the eyes of whom, etc. Then, "taking on" the bodily attitudes (and tastes) that are assigned to our sex in a given society is seamless, but neither natural nor logical - it's simply invisibly consensual, but not more or less absurd than "taking on" attitudes that a given society doesn't assign to this or that sex. Then, many people "feel" they belong to the other sex, and endorse (consciously or not) the gendered attitude that are attached to it, and sometimes it also goes with the sexual preference (not even any apparent contradiction there). Then, people who are attracted to one sex aren't necessarily attracted to all the gendered attitudes that are supposedly related to it. And, of course, not as many homosexuals "take on" opposite gender roles as the stereotype implies.

Seriously, gender it a crazy can of bouncing worms, of which our society only makes a few visible (strengthening its the idea of normality through the "invisibilising" of its actual diversity). But humans, in practice, are so crazily varied on that sort of stuff that you'd be hard-pressed to even invent a "logic" in relation to which some behaviours would be "illogical"...

I was thinking of starting the replacement process tomorrow if Krypsyn doesn't answer by then.