Right on Julie.
David Bowie himself couldn't even budge the Gender Line for men.
Popular thinking holds that men are the superior sex, that they have it made, etc. etc. But that "freedom" comes at a price, namely, that masculinity is narrow and restricting should one choose to escape from it.
A lot of gender therapists I've read argue that MtF's have a harder time socially adjusting because there are very few opportunities for them to socialize until they pass reasonably well. FtM's, in contrast, enjoy a lot of wiggle room in their expressions of masculinity.
But Julie asked, "Why are the gender lines so defined for men?" Evolutionary psychologists probably have an answer having to do with mating, survival, and some such.
If I had to hypothesize, I would actually argue that it's cultural. Feminism effectively widened the gender line for women...women were literally duped into becoming men during the 50's and 60's. They started smoking cigarettes, wearing pants, cussing, behaving masculine. Nobody consciously questions the popular culture - they accept it like a religion. Ask a woman today if she feels self-conscious about doing "typically male stuff" and she'll just laugh at how absurd the question is. Ask a woman from the 20's or 30's how she would feel about doing those things, and she'd tell you how silly it would be for a woman to cross the gender line.
I primarily believe that feminism gained so much force because our flailing socialist economy needed an injection of cheap labor (women) it order to stay afloat post WW2. Breaking up the nuclear family unit is also a cornerstone of any socialist state (the State = your family, Tom Brokaw is your new father, the TV and public schools will raise the children.)
@ Brielle
Psychological models of categorization clearly favor feature multiplication rather than addition. This means that, rather than checking off a list of features that make a person male or female, we give more credit to certain features over others. For example, when determining whether a person is human or a mannequin, we look to whether the person is living - the existence of arms/legs/clothing will not tell us.
Faces are typically what we look to when there is gender ambiguity. Very few women have brow bossing. Out of the entire body, the forehead is one of the strongest cues to a person's gender. Our brains AUTOMATICALLY determine a person's gender before we're even conscious of the classification. So rather than spend 20-30 seconds mulling it over, our brains just take shortcuts and favor the evidence from a few statistically-relevant pieces of data. The way a person walks, moves, and talks is also a massive indicator.
Another way of thinking about it: some guys have manboobs, and some girls have big noses or wide chins, but almost no girls have brow bossing, and almost no guys have a truly effeminate walk (even the gay ones).
How would you classify this person: no brow bossing and smooth forehead, somewhat wide and bumpy nose with no upturn, medium-width and height chin, female clothing, clunky gender neutral walk. A lot of people would probably think it was an unattractive woman.