Honestly nobody knows what cause or change peoples sexuality, if they did sociaty would probably make gay abortions and anti-gay pills who actually worked.
they have clues but you cant prove anything for sure.
From my experience its posible people change sexuality, but its generally rare and the change are more likely to be someone who finally become open about how they feel since we live in a world where we have to fit into narrow boxes which obviously not everyone fits.
I dont think homones really have that huge effect on changing peoples sexuality as some say. its more people who take homones make change emotionally. For some people getting homones and a body they feel confortable gets a positive inpact on there sex or dating experience, they somehow become more free because they got more confidence within themself and they may also get to express there need in a way they was afraid of before. A lesbian woman may never really had wanted to be with another women, not because she didnt want to but because she didnt like to be previewed as a man, but as she transition she may get more confortable being a woman, and finding women who sees her as she is, and it could change how she feel.
I seen many who experience a bit of change because there life change, its not nessesarry a change on sexuality, I dont feel I seen so much of that, but a change on interest in sex or dating or how troublemakers became more claim or depressed shy people got more outspoken simple because they got more confident within themself.
So its a diffrent of what you really want but dont do cause of fear or insecurity, or what you actually dont want simple because you dont.
im bisexual and it havent really change before or after T. I did became more sexual as I got more confortable in my body, and confortable enough to show it and it more what I mention above.
being Bi I had alot of worried of my sexuality and how it would infect me or change for a period. First I was sure I was straight cause I liked a girl from my class, and I was very afraid I wasnt obviously because being
gay was "bad" I know its not and my parrent suport me, but we dont live in a suportive world and being gay would just add another struggle to my already difficult life. therefore I got really sad when I actually felt for a guy and couldnt deny that part of me any longer. I cried for a time but then I moved on. when I was to take testostorone I had started getting more confortable with how I felt and I got abit worried, how it would be if I turned 100% gay or straight, it was not something I wanted, not because of opression but because it was unfamiliar and I had no idea how I would handle that or how it would infect my life.
it havent really changed anything but bottom line is that its not something I have controll over, No matter if I take homones or not I cant controll who I feel sexualy attracted to or not, If I could daim my life would had been SO easy.
but really you shouldnt worry about it cause its not something you can really have the contoll of, its like worried about you might be droven over by a car, and yes you might cause some do, but you might also never do and then you have wasted your whole life worried about it.
If you all deep honestly are straight and into girls, not because its "the right choice" or because "its simple" or "normal" and theres nothing telling you that you are into guys, then your not anymore likely to change your sexuality than other cisguys, so pack your worries down in a box and send them away.
if you one day find yourself into a guy that make you questionate then you can unpack the box and start worry and questionate and take those problems there by seeking the suport you need, but dont deal with this unless it issues for you. its my advice.