+Daphna Joel _et al._ [argue](https://www.pnas.org/content/112/50/15468) [that](https://www.pnas.org/content/112/50/15468) human brains are "unique 'mosaics' of features" that cannot be categorized into distinct _female_ and _male_ classes, because it's rare for brains to be "internally consistent"—female-typical or male-typical along _every_ dimension. It's true and important that brains aren't _discretely_ sexually dimorphic the way genitals are, but as [Marco del Guidice _et al._ point out](http://cogprints.org/10046/1/Delgiudice_etal_critique_joel_2015.pdf), the "cannot be categorized into two distinct classes" claim seems false in an important sense. The lack of "internal consistency" in Joel _et al._'s sense is exactly the behavior we expect from multivariate normal-ish distributions with different-but-not-vastly-different means. (There aren't going to be many traits where the sexes are like, _four_ or whatever standard deviations apart.) It's just like how sequences of flips of a very Heads-biased and very Tails-biased coin are going to be unique "mosaics" of Heads and Tails, but pretty distinguishable with enough flips—and indeed, with the right stats methodology, [MRI scans can predict sex at 96.8% accuracy](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6374327/).
+
+Sex differences in the brain are like sex differences in the skeleton: anthropologists can tell female and male skeletons apart (the [pelvis is shaped differently](https://johnhawks.net/explainer/laboratory/sexual-dimorphism-pelvis), for obvious reasons), and [machine-learning models can see very reliable differences that human radiologists can't](/papers/yune_et_al-beyond_human_perception_sexual_dimorphism_in_hand_and_wrist_radiographs.pdf), but neither sex has entire _bones_ that the other doesn't, and the same is true of brain regions. (The evopsych story about complex adaptations being universal-up-to-sex suggests that sex-specific bones or brain regions should be _possible_, but apprently evolution didn't need to go that far. Good news for antisexism!—relatively speaking.)
+
+Maybe this should just look like supplementary Statistics Details brushed over some basic facts of human existence that everyone knows? I'm a pretty weird guy, in more ways than one. I am not prototypically masculine. Most men are not like me. If I'm allowed to cherry-pick what measurements to take, I can name ways in which my mosaic is more female-typical than male-typical. (For example, I'm _sure_ I'm above the female mean in [Big Five Neuroticism](https://en.wikipedia.org/wiki/Big_Five_personality_traits).) ["[A] weakly negative correlation can be mistaken for a strong positive one with a bit of selective memory."](https://www.lesswrong.com/posts/veN86cBhoe7mBxXLk/categorizing-has-consequences) But "weird" represents a much larger space of possibilities than "normal", much as [_nonapples_ are a less cohesive category than _apples_](https://www.lesswrong.com/posts/2mLZiWxWKZyaRgcn7/selling-nonapples). If you _sum over_ all of my traits, everything that makes me, _me_—it's going to be a point in the _male_ region of the existing, unremediated, genderspace.
+
+Okay, maybe I'm _not_ completely over my teenage religion of psychological sex differences denialism?—that belief still feels uncomfortable to put my weight on. I want to believe that there are women who are relevantly "like me" with respect to some fair (not gerrymandered) metric on personspace. But, um ... it's not completely obvious whether I actually know any? Most of the people in my robot cult (and much more so if you look the core of old-timers from the _Overcoming Bias_ days, rather than the greater Berkeley "community" of today) are male. Most of the people in my open-source programming scene are male. These days, [most of the _women_ in my open-source programming scene are male.](/2017/Aug/interlude-vii/) Am I not supposed to _notice_? I could _assert_ that it's all down to socialization and self-fulfilling prophecies—and I know that _some_ of it is. (Self-fulfilling prophecies [are coordination equilibria](/2020/Jan/book-review-the-origins-of-unfairness/).) But I can't assert _with a straight face_ that all the gaps will vanish after the revolution, because _I've read the literature_ and can tell you several observations about chimps and [congenital adrenal hyperplasia](/images/cah_diffs_table.png) that make that seem _unlikely_.
+
+I want to speculate that the nature of my X factor—the things about my personality that let me write the things I do even though I'm [objectively not that smart](/images/wisc-iii_result.jpg) compared to some of my robot-cult friends—is a pattern of mental illness that could realistically only occur in males.
+
+I was once told by a very smart friend (who, unlike me, is not a religious fantatic), "Boys like games with challenges and points; girls like games with characters and stories."
+
+I said, "I like characters and stories! I think."
+
+He said, "I know, but at the margin, you seem suboptimally far in the challenges and points direction. But that's fine; that's what women are for."
+
+And what evidence could I point to, to show him that he's _bad and wrong_ for saying that, if he's not already religiously required to believe it?
+
+_Alright_. So _in principle_, you could imagine having a PersonApp that maps that point to the female region of configuration space in some appropriately structure-preserving way, to compute my female analogue who is as authentically _me_ as possible while also being authentically female, down to her pelvis shape, and the proportion of gray matter in her posterior lateral orbitofrontal cortex, and—the love of a woman for a man. What is she like, concretely? Do I know how to imagine that?
+
+Or if I can imagine it, can I _describe_ it in this blog post? I am presently sorrowful that [(following John Holt)](https://www.greaterwrong.com/posts/S8ysxzgraSeuBXnpk/rationality-quotes-july-2009/comment/DtyDzN5etD4woXtFM) we all know more than we can say. I have mental models of people, and the models get queried for predictions in the course of planning my social behavior, but I don't have introspective access to the differences between models. It's easier to imagine people in hypothetical situations and say things like, "That doesn't sound like something she'd _do_, but _he_ would" (and be correct), than to say exactly it is about her character and his that generated these predictions (such that [my words would paint a picture in your head](https://www.lesswrong.com/posts/YF9HB6cWCJrDK5pBM/words-as-mental-paintbrush-handles) that would let you make your own predictions about her and him without having met them)—just like how you're better at recognizing someone's face, than at describing their face in words in enough detail for an artist to draw a portrait.
+
+As a _first-order approximation_, I do have a sister. I think the family resemblance between us is stronger than with either parent. We're about equally intelligent. (OK, plausibly she's smarter than me; [the SAT is pretty _g_-loaded](https://www.gwern.net/docs/iq/2004-frey.pdf) and her 1580 (out of 1600) solidly beats my 2180 (on [the out-of-2400 scale used between 2005 and 2016](https://en.wikipedia.org/wiki/SAT#2005_changes,_including_a_new_2400-point_score), such that 2180 proportionally scales down to 1453 out of 1600).) Our dark hair curls into helices with similar radius. We even have similar mannerisms, I think? She's 5′6½″.
+
+But in a lot of ways that matter, we are _very_ different people. When you compare representative outputs of what we've _done_ with our (roughly) similar intelligence—her chemistry Ph.D. from a top-10 university, my _batshit insane_ secret ("secret") blog about the philosophy of science and the etiology of late-onset gender dysphoria in males—it ... paints a different picture.
+
+Of course same-sex siblings would _also_ be different pictures. (Identical twins aren't _duplicates_ of each other, either.) But the advantage of having a sister is that it gives my brain's pattern-matching faculties a target to [sight](https://en.wikipedia.org/wiki/Sight_(device)) against. As a _second_-order approximation, my female analogue is close to being somewhere on the vector in personspace between me and my sister. Not exactly on that line, because the line spans both the difference-betwen-siblings and the difference-between-sexes. But the angle between the line between me and my sister, and the line between me and my female analogue, is the [arctangent](https://en.wikipedia.org/wiki/Inverse_trigonometric_functions) of the difference-between-same-sex-siblings and the difference-between-sexes, which is small if sex differences are a lot larger than same-sex sibling differences (with respect to whatever metric on personspace we're using).
+
+(All this is in accordance with "Everything is a vector space" philosophy implied by this blog's [TLD](https://en.wikipedia.org/wiki/Top-level_domain). (If it turns out that something _isn't_ a vector space, I'm not sure I want to know about it.) I can hope that my description of the _methodology_ is valuable, even if your brain's pattern-matching faculties can't follow along with the same example, because you haven't met my sister and only know the aspects of me that shine through to the blog.)
+
+Okay. Having supplied just enough language to _start_ to talk about what it would even mean to actually become female—is that what I _want_? I mean, if it's reversible, I would definitely be extremely eager to _try_ it ...
+
+I had said we're assuming away engineering difficulties in order to make the thought experiment more informative about pure preferences, but let's add one constraint to _force_ the thought experiment to be informative about preferences, and not allow the wishy-washy evasion of "I'm eager to _try_ it."
+
+What if I can't just "try" it? What if the machine can only be used once? Come up with whatever frame story you want for this: maybe the machine costs my life savings just to rent for two minutes, or maybe the transformation process is ever-so-slightly imperfect, such that you can't re-transform someone who's already been transformed once, like a photocopy being a perfectly acceptable substitute for an original document, but photocopies-of-photocopies rapidly losing quality.
+
+In that case, if I have to choose ... I _don't_ think I want to be Actually Female? I _like_ who I am on the inside, and don't need to change it. I don't _want_ to stop liking challenges and points as much as I do—and if I don't know enough neuroscience to have an _informed_ preference about the ratio of gray matter in my posterior lateral orbitofrontal cortex, I'm sure it's _probably fine_.
+
+At the same time, the idea of having a female body still seems like _the most appealing thing in the world_. If artificial superintelligence gives me BodyApp for a subjective year and tiles the _rest_ of our future lightcone with paperclips, that's _fine_; I will die _happy_.
+
+So, I guess ...
+
+If I'm being _really_ honest with myself here ...
+
+And I successfully make-believe that I can tell the truth with no consequences on my secret ("secret") blog even though at this point my paper-thin pseudonymity is more like a genre convention rather than providing any real privacy ...
+
+I guess I _want_ to be a normal man wearing a female body like a suit of clothing.