If you want to know the hard truth of my opinion...
I believe that a very large proportion of the transgender population believes in controllable attributes like posture, because they are not passing with less controllable ones.
And again for one of those disclaimers you enjoy, I am not talking about you in particular, I don't know you or what you look like.
But what we want unfortunately doesn't change reality. I wish the reality was that everyone was happy, I wish that everyone could be who they are without fear of discrimination or prejudice. I wish I didn't have multiple sclerosis, I wish I wasn't transgender, I wish the government would stop interfering and regulating in matters I feel they have no moral right to interfere in. I wish bad things didn't happen to good people, and I wish good people didn't feel compelled to do bad things.
I wish this forum would embrace the concept of harm reduction and change its policies regarding self medication.
Unfortunately this isn't a perfect world, virtually none of those things are the way I wish they were, and unfortunately some people don't pass.
My belief is that hormones and voice are the number one controllable influence in a persons passability. And I don't believe the 'way' you speak, the words you use, the way you walk, or any of that, has any appreciable influence. My belief is if you put a cisman in a dress, give them long hair, tell them to walk feminine, and put make up on them, then most people may well refer to them as female. Especially people who's jobs depend on customer satisfaction. But those people are humoring them. They are doing that because they don't want to offend them, start a fight, loose their jobs, believe in their right to identify however they want, etc. But ultimately the majority of people see this cisman as a male wanting to be identified as a female, not as a female.
I believe this because I know a lot of androgynous looking people and I know how my brain works in this regard. And I can only assume most people perceive it the same way.
Maybe I'm wrong, maybe most people would see the aforementioned cismale as biologically female, but personally I doubt it.
Unfortunately in life, sometimes things really suck and there's nothing we can do to change them.
Accept the things we can't change, change the things we can, and know the difference.
I'm tempted to not even post this, and I hope nobody is hurt if I do. If someone gains comfort in something I don't ultimately believe is true (religion), then who am I to change their mind?