So maybe it's not so far fetched to suggest that people are born with a given orientation?
Why would or should it be far fetched if one considers Human Genetic Variation and the hundreds of million variants of genomes.
The odds of it being biological far outweigh those of it being psychological.
The fact that for decades , some unfortunate individuals were subjected to disgusting variation of "conversion therapy" with no discernible viable results only shows that one cannot change what is inherently natural.
If it was purely psychological the results would have been different.
The simple truth is we are not seeing an increase in Trans or Gender Dismorphia people within society, they have always been around and been part of society. The reality is they are finally able to be themselves and not have to hide or blend in due to shame, predjudice, or bigotry.