Transgender is a blanket term that covers all people whose sense of gender identity does not match their physiological sex. For some transsexuals, there is a genetic explanation of this (usually something like an XXY triplet instead of the usual male XY chromosome pair); for the rest of us, the explanation is less clear. The most probable cause is a variation in hormone levels at a critical point in pre-natal development, probably around the twelfth week, which in turn causes the brain to develop gender characteristics that do not match the physiological or genetic gender of the developing fetus. This assumes that some aspect of gender identity is hardwired into the brain, but considering that structural and organizational differences do exist between male and female brains, this assumption seems reasonable.

Most transgendered people are aware of their difference at a very early age. Cross-gender behavior patterns, including cross-dressing, typically appear by age 5. This would support theories that transgenderism is rooted in developmental conditions, that it has a physiological origin, and that environment has little influence in the origin of transgenderism. One implication of this is that transgenderism is permanent, and that no amount of therapy, drugs, denial, conditioning, rejection, bribery, cajoling, badgering, nagging, or anything else will make it go away. If it's "only a phase," then the phase lasts from age 5 through death. One known cure, which isn't appropriate for everyone, is surgery--changing the body to match the mind.

If the environment cannot create or prevent transgenderism, it can certainly influence the range of expression available to the transgendered person, usually in a negative way. Cross-gender behaviors are rarely tolerated by family, friends, schools, churches, strangers, or anyone else. Even the occasional fad of encouraging little boys to play with dolls will only send a mixed message; as soon as that little boy puts on his sister's dress, he will learn the limits of free expression, and of tolerance for the cross-gender behavior that was initially encouraged.

As a result of this environmental influence, the transgendered child learns to behave in ways that are consistent with the external gender, and to hide or suppress the internal gender. (I had to learn to be male, just as I now have to unlearn being male.) The results of such suppression can include emotional dysfunction, depression, lack of trust, self-doubt, and much more. The fact that all of this starts before age 7, during the formative years for the child's personality, implies that emotional and personality problems will be deeply rooted, and may have effects that last a lifetime.

It is true that our society is much more tolerant of cross-gender behavior in girls than it is with boys, but even then, there are limits. I remember coming out to a group of friends, and hearing about a girlfriend that one person grew up with. She'd been a tomboy, but when she was told that she would grow up to be a woman, with dresses, and babies, and periods, and everything else, she was crushed. She denied it; she ran away and hid and cried. My heart went out to that girl when I heard about this; I knew that she was one of us. And none of us were there to support her.

No matter what we do that is "tolerated" by society, there are always limits of tolerance. When that tolerance is exceeded, it is not society that pays the price. We continue to pay that price until we turn to embrace and nourish our difference.