The disorder that causes them to imagine they are a different gender/sex than their DNA. This is not about opinions. Homosexuality (different from trans clearly) is wrong of course, but is a "choice/opinion" not a genetic aberration (i.e. "made that way").
This has been "settled" for a long time. Only the evildoers in society who don't love these people by encouraging this bad behavior vs. getting them the help they deserve are making it worse.