It's a painful process, and the girl suffers a lot.
But, you cannot blame the surroundings: her father fully supports her, her ballet teacher fully supports her, nevertheless, things go wrong.
This negates the idea that we would have been happy, if it were not for the external imposition of patriarchy and binarial logic constraining us to gender identity.
In their experience, the distortion, pervertion, suffering, which is inscribed into human sexuality as such comes out, they are, as it were, sex at its purest, sex at its most antagonist.
Cisgenders are constantly bombarded by the social-constructionist message, using Judith Butler's term.
Yet, it becomes essentialist as transgender people often express their longing to "live authentically as my best self".
Of course, gender is symbolically contructed. It is, in some sense, a choice. One's gender identity is not biologically determined.
However, authentic free choice, by definition, as we learnt from Kant Schelling etc., at its most radical, is always experienced as a neccessity. The choice's already happened, which means it's an unconscious choice. That's for me a very simple Freudian solution of "is it socialconstructionism or determinism?". It's a free determinism, from the standpoint of one's conscious ego. It is determined, but at a deeper level, you are responsible for it.