Now, this is just my own little story about how this works, and it may be completely wrong. But the punchline here is the idea that if we did a better job of accepting individuals without trying to push them toward traits predicated on gender, we would have fewer individuals who feel like their personalities are better suited for the other gender.
I'm going to turn this around the other way for a minute, as a kind of thought experiment, because I'm not so sure it's traits.
For those who aren't transgendered, and don't have any uncertainty about their gender, what would it take to feel--not to pass as, but to
feel--like the opposite gender, 24 hours a day?
Personally, being male, if someone expected me to get cosmetic surgery to appear female on the outside, or to dress in clothes that the opposite sex wears in my society, or trained me to take on mannerisms of the opposite sex in my society, I think I'd still feel male on the inside. If they taught me stereotypically female skills--some of which I actually do have, like an interest in sewing and cooking, I think I'd still feel like "a man who sews," as I do now.
In fact, I don't think there's any trait I could adopt, which would make me
feel female, no matter how well I might theoretically be trained to pass as a female in society. I'd always be "a man in a dress" or "a man who had his privates surgically worked on," or "a man who wears makeup," or "a man who stops and asks directions instead of driving till he figures out where he is."
Maybe,
maybe, I could try to imagine what it would be like to be a woman, the way an actor might get in character, for a short while, but I don't think it would last, and I don't think it would really feel like "me."
Maybe I'm unusual in that, but it's what has always given me an intrinsic sympathy with transgendered individuals. If I can't imagine any outward thing, in appearance or socialization, which would make me feel male on the inside, I can sympathize with someone who is just as certain they're female (or male), despite society and their appearance identifying them as the opposite.
Maybe a sense of maleness or femaleness is just all socialization, and it would be possible to have a society where there was no male or female differentiation except in genitalia. But has there ever been such a society? Would it even be possible, considering the different affects of testosteone and estrogen on personality as well as secondary sex characteristics?