The adoption analogy is an interesting one which I have a personal interest in, I saw it brought up on Twitter earlier also.
I can see parallels re the legal status of a gender (or gendered) role. However both situations appear to have progressed in different directions over the last few decades.
Years back many children were not informed they weren't biologically related to their adoptive parents and it was often encouraged to be this way. Which I do consider to be a lie by omission.
More recently openness about biological truth and origins is seen as best practice because it's agreed that not acknowledging truths is psychologically harmful to those involved.
The situation with legal trans people seems to have gone in reverse. It used to be accepted that trans people were born a given sex and biologically remained that sex even though their legal sex was different.
This seems to be the position that the trans people posting here take.
Now the current thinking has gone in the direction of trans people always having been the opposite sex therefore there is no 'before' and no distinction allowed between the biological and the legal.
I suppose what I am saying is that there are similarities in the two things but the accepted thinking about how to deal with biological truths seem to be poles apart.
I'm sure someone else can add more to this. I'm an adopted person from way back rather than an adoptive parent so I'm viewing it from that side.