Why?

Because when you come at me with an insipid question such as "How can it be both innate and a social construct hur hur hur" when I never said it was, you clearly have a pre-conceived agenda to try and discredit trans people.

You don't get to be arrogant by action then whine about not receiving the most civilised response.

And how do we know? Because the experiences of trans people are broadly the same, as shown by research for nearly 100 years. Research that you quite clearly prefer to ignore to suit your narrative.