Nice try Lost. Shoehorning the BBC in there at the end is quite ingenious. Emmerdale is on ITV, but to you they are probably co-conspirators.
The problem with the biological determinism (i.e. that you can only be the sex that you were born as) argument is that it doesn't quite tell the whole story even from the biological perspective. There is increasing evidence that the brains of trans people are somewhat different to the average brain for someone of their biological sex. i.e. there is actually a measurable biological difference in the trans population from non-trans. Here is a pop science article about it, there have been many other studies since then;
Imaging studies and other research suggest that there is a biological basis for transgender identity
www.scientificamerican.com
When our society has recognised and digested this (scientific) truth, we can perhaps have a more nuanced debate about what is the appropriate treatment for this group of people (if any) instead of dismissing it as 'nonsense'.