Reflect on an area in our natural world without any anomalies and you will genuinely hard pressed to think of any. Eventually you will arrive at the inevitable conclusion that perfection and uniformity are not possible. So why would sexual and gender identity be the only areas untouched by this variability? It would be possible to predict on that basis alone that people like us exist even if one had never met or heard of the concept of transgender or transsexual individuals.
Those who read my blog know that I am absolutely sold on the idea of gender identity as a continuum. You have intersex people who identify as one gender or the other or both and they are easier to believe since they carry the physical signs of difference but what is inside the brain is not as simple to diagnose.
You have male bodied people who identify as female and female bodied who identify as male with no detectable signs other than their own insistence. But even then the predictability of anomalies found elsewhere should bolster our conviction that transgender people are not making things up.
Therefore we can take solace in the fact that we are part of wonderful tapestry of variability that is found in this strange and magical universe.