Consistency and freedom
We cannot have double standards, it is quite unconvincing when we change our arguments according to what is convenient on a case by case basis.
When it came to gay rights, some years ago, we lifted the “born this way” banner and insisted on the strength of biology. Nature had decided and there was nothing we could do about it. We had to abide if we wanted to be happy. Acceptance of nature was the key; no room for choice left. We asked for marriage equality on the basis of this argument.
When it comes to transgender rights, we reject the significance of nature. Sex does not matter. What matters is gender which is a social construct. We ask for the right to choose (or not to choose) gender at will. Biological sex has zero significance.
I never believed in the existence of a “gay gene”. I always believed that things were more complicated and that upbringing played a role in defining my homosexuality. I also thought that this did not really matter. What matters is to be given the right to choose, the freedom to choose to live life the way we believe it will bring fulfillment. This freedom should be given, it is a prerequisite to happiness. The duty of society is to guarantee this right (under the condition that you harm no one).
And I cannot disclaim nature which defines biological sex. However, humans (and only humans) progress in freedom from nature through civilization. It is civilization which transcends biology, it is progress of technology and of society built on fair play that render the division of social roles between men and women obsolete. We are both children of nature and culture. Society has to ensure equality regarding matters of gender identity.
I choose none between the dogmatic support of a “born this way” absolute biological truth (regarding gay people) and the equally dogmatic rejection of sex (regarding transgender people). The road ahead lies somewhere in the middle. It balances the freedom to choose happiness under the consideration of boundary conditions set by nature.
The fight for equality requires consistency. The adoption of opposing positions according to argument convenience collapses under serious scrutiny. It is also damaging. It gives hold to those who claim that it is not a matter of life, of equal rights in life, but a matter of lifestyle.