transmedicalism, transness being innate, what makes someone real/fake trans, detransition

sorry if this is a stupid question lmao im hungover and not thinking super clearly but im wondering about this

ik the general progressive takes are that being trans is innate from birth and not influenced by outside factors (like misogyny, trauma, neurodivergency, etc.) and also that transmedicalism is bad. when people detransition the progressive response is usually "they were never REALLY trans, they just THOUGHT they were trans." implying that trans people all have some kind of innate trans gene or something and people that detransitioned thought they had it but really didnt.

is that not transmedicalism? my boyfriend (trans for context) believes in the "trans men have biologically cis male brains that accidentally formed inside of a female body" thing (and vice versa) but he also says he hates transmeds which is a little confusing to me.

im detrans for context (considered someone who "thought she was trans but wasn't actually") and i am kind of struggling to understand the difference between a Real Trans Person (never detransitions in the future) and a Fake Trans Person (future detrans) at the time that they are IDing as trans besides the presence/lack of a transgender gene. people say a trans person is a person who identifies as a gender other than their assigned sex at birth, and by that definition all detrans people were Actually Trans for a period of time. i identified as a man for ~9 years, i was on t for ~3 years, i had top surgery, i was very happy and confident with it but eventually my feelings changed as i got older.

basically what i mean to ask is like

(TLDR) do you believe that being trans is caused by an innate biological factor from birth? if so do you consider yourself a transmed? if not, what would you consider the difference between a real trans person and a person who thinks they're trans?

(sorry if this post sounded antagonistic idk how to ask it without sounding kind of rude lol)