I would like to think people should still be able to decide on their own in the absence of judgement or coercion
What do you mean by this? While you believed that people had no choice about being gay/trans, you didn't seem to be at all bothered by the lack of choice.
With my previous (incorrect) knowledge, attempting to influence someone's sexuality had no redeeming features. Its only effect was to create confusion, self loathing and other negative effects/emotions in adolescents. If, however it can be effected by the environment then there exist situations, possibly controllable situations where children can be systematically influenced to one sexuality or other.
My immediate reaction is that people should still be able to figure it out for themselves, but the situation is less black and white than before. If for exam...
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.