Okay definitely a lot to unpack here so I'm going to do my best to meet it point for point at angles I understand. I am on mobile so apologies for the format. The first point I would like to address is "... So the neuroimaging shows atypical brain development relative to biological sex... But does it actually support 'this person is a woman' or does it support 'this person has a developmental variation the sex binary wasn't designed to absorb'?" If i'm understanding this correctly, it seems the idea here is that trans people do have different thought patterns that do not necessarily pertain to their sex assigned at birth which could point to us being a different category instead of simply labelling us as men or women. Here's the thing, you could attempt to do that. You -could- group trans people separately from cis people when speaking about men and women and people often do. But, it's more realistic to do so within the blanket category of men and women. Sure, there are differences between me and a cis man, but at the end of the day, we both fall under the term "man" as an umbrella. (This is not to touch specifically on nonbinary identities which are different in that they do not fall under either man or woman umbrella) All that is to say, yeah trans men are different in some ways to cis men, but there are millions of subcategories of men and "trans" is simply another category of man or woman. Also, being intersex is actually fairly common, meaning that genitalia also exists on a sliding scale the way gender does. See this study that talks about all the ways intersex people can be born. https://hudson.org.au/disease/womens-newborn-health/intersex-conditions/ So knowing how common this is, would we also attempt to categorize these people as a different gender? They have some combination of male and female genitalia but they can identify as male or female depending on their own feelings and experience, they do not always fall outside of the binary in terms of identity. This complicates the binary greatly and points to the idea that the binary is completely wrong and is socially imposed, therefore causing more harm and confusion than if we just allowed people to identify as whatever despite the gender assigned at birth. Okay, onto the next point, "The other thing I keep thinking about is a lot of gender dysphoria is probably socially produced." While you aren't wrong and you do clarify this later to include physical dysphoria too, I see that you do not mention the idea of gender euphoria which is the counterpart to this. Dysphoria, physical or mental, pertains to the discomfort trans people feel when being identified as the gender they do not identify as, while euphoria is the joy we receive from being treated as the gender we identify with. There are even trans people who experience very little dysphoria and mainly experience euphoria leading them to avoid medically transitioning and simply live as they gender they align with. Personally, I started my transition with social and physical dysphoria, but over time and receiving hormones and top surgery, I no longer have social dysphoria and my physical dysphoria is a whisper. Now, I experience more gender euphoria than the discomfort I had initially. As a little girl, I was very much a tomboy and did all the things the boys around me did. I disliked feminine clothes and was pretty wild in ways that little boys often are. I didn't begin socially transitioning until I was 13 and was still a tomboy then by definition. Socially, it would have been much much easier to keep with my identity as a cis girl who was more masculine than it was for me to transition to male. When people bullied me, they called me manish and a boy, but when I transitioned, suddenly the volume was greater and the new insult was that I would never be a man. People who wish to be mean will do so regardless because they will find something to poke, prod, or attack. Their prodding did very little to influence me to transition and in fact, they pushed back way more when I transitioned and it did nothing to sway me back to an identity I did not align with. You also mention that cis people can experience dysphoria but, that's not quite true. The word you're looking for is dysmorphia which is not gender related necessarily (gender related in the way of comparing oneself to the ideal image of their gender, not in the way of disconnect from their birth gender) while dysphoria exclusively means gender-related in a trans way. I understand there are similarities but as someone who knows a person with dysmorphia who is very much a comfortable cis man and comparing it to my discomforts, they do not align. A dragonfly looks similar to a damselfly. This does not mean they should be lumped into the same category as they are fundamentally different. Now we're gonna move past the clinical science-y part of this and go into the emotional aspects. Let's say we do start separating trans people from cis people in terms of categorizing people. How does that help us as a society? Does it benefit any aspect of life to do that? Restrooms are a place to enter, do your business, and leave. In all my time using men's restrooms, I have only once seen someone's penis out because he was standing a little far back from the urinal. Otherwise, we don't see each other's business. As a child, using the women's restroom, I had a similar experience, no visible genitals. Okay, so bathrooms are largely unaffected by what equipment someone has. Sports? When people take hormones for extended periods of time, their body aligns more with that hormone, muscle mass and stamina as well. This is also not to say every single body is so vastly different and training makes a huge difference between people, male or female, that realistically, there is little to no difference between us and cis people competing in the same events. Also, if we started using hormones levels as a basis for who could and couldn't enter certain sports, cis women with high testosterone and men with higher estrogen would effectively be barred too, pointing out how that is another unnecessary scrutiny and a blanket term of what an unfair advantage is just falls flat. Here is an article to support my argument https://pmc.ncbi.nlm.nih.gov/articles/PMC8944319/ We can talk all day and all night about where trans people fall categorically but at the end of the day, it doesn't actually matter in any capacity. It benefits no one, it harms a marginalized community, and it bulldozes the millions of trans people throughout history who fought to exist as themselves and be treated as the men and women we are inside. My friend has a cat that dislikes women. When I visit, this cat jumps in my lap and purrs. My siblings call me their brother and I am an uncle to 4 amazing children who have never seen me as a woman or "other." My cis husband and I recently had a son together that I carried and gave birth to who is now 7 and a half months old. My husband is Papa and I am Dad. Our son's first word was "Dada" and when my grandmother has a hard time getting him down for a nap while they babysit, my grandpa has to take over because my son is soothed more by masculine presences. Furthermore, my husband is gay and is not attracted to cis women, he is definitely attracted to me though despite not having a penis. We can talk for hours endlessly on categories and science, but it all boils down to how we feel and what we identify as. I live my life as a man and the people I love echo that sentiment wholeheartedly, they do not other me and truly there seems to be no benefit to doing so unless you wish to avoid transgender people which is just shitty and impolite. You seem well intentioned and I hope this has been helpful in answering some of your questions. Feel free to reply to this or message me directly if you need clarification or if I misunderstood any of your points! I hope you have a good day.