I see where you're going with this, but I still respectfully disagree - gender orientation (whatever the hell that is - do you mean trans people?) is not the same thing as sexual orientation, which is specifically "who you are attracted to", not "the gender you identify as". It's about sex, not gender.
And if experience can shape someone's sexual orientation, then the "pray the gay away" type of efforts would have succeeded. A lot of homosexual people in the past did not want to be that way, and yet no experience they had, or sought out, managed to change who they were attracted to.
So yeah, the argument "experience can shape your sexual orientation" is, IMNSHO, complete hogwash and at odds with reality as we've seen in the homosexual demographic.
No, they wouldn't.
“Shaped by experience” is not “choice” and “at least partially” does not mean “definitely specifically as to gender orientation”.