m vs f brains?

I have always had a fairly strong stance on whether males and females were capable of the same things. I have conceded that males and females are biologically different due to differences in our chromosomes, but have always ascertained that the discrepancies between individual people were so large that, although on average males may have some difference to females, in general you could not assume those differences for an individual. Thus, you cannot assume a person would be incapable of a certain job, for example, based on their gender.

Gender is an interesting thing. Do we have these gender roles because of our biology? Perhaps men were better at leading or hunting because they have more testosterone and are therefore more generally aggressive. But there have been better women leaders and hunters and fighters. Do women stay at home because they have to have children? But there are women who can’t have children, or won’t have children, or are terrible mothers. There are households where the father is a far better caretaker than the mother – not everyone is “naturally inclined” to look after children. But here is where it gets tricky. Yes, a lot of the arbitrary social constructs like household work vs outdoor work were probably imposed by history and society, but what “gender constructs” are an actual result of our biology?

This reminds me of a time when my dad assumed that male and female brains were different, and I vehemently opposed it. In my classes at uni they had dismissed the whole thing about males having better spacial awareness than females (and boys are probably better at video games because they grow up playing it whereas girls are given less opportunities to play it since it’s a “boy activity” according to society), males have bigger brains but they also just have bigger bodies and, anyway, big brain do not equal higher intelligence. I think I read something where having a bigger corpus callosum meant women could transfer information faster from one hemisphere to the other but surely (if that’s true) that varies on an individual level, too? Perhaps I did not think about the effect that our different hormone levels had on our brains, so I probably needed to do more research in that area. It did not strike me as important because people who were biologically male or female could still be very similar and vary in different ways. But then I came across something that threw a spanner into my argument: transgender people.

Transgender people confused me a lot because, frankly, I am not trans and therefore do not understand the type of identity crisis they would go through. How can one know that they are male when they look female, and vice versa? I know, it is a very generalised, layman’s view of transgender issues so I apologise if I offend anyone, but that was the general confusion I faced. To me, the brain was genderless and your body was just your body. I had heard about body identity integrity disorder – for eg. you absolutely do not believe your arm is your arm and therefore want it gone so you get it surgically removed and actually feel good about it afterwards. There is also body dysmorphia, where you are excessively stressed about a certain aspect of your body. However, neither of these explain everything about trans people. Some people are born genderless or with the ability to become either gender because of certain mutations, such as being born with XXY, XXX or XYY etc. sex chromosomes instead of XX for female and XY for male. But again, this doesn’t explain all of it.

I asked a friend if there was a genetic basis for all this – she had been telling me about how being gay seems to be transferred from the mother’s side and may be linked to a mutation on the X chromosome. She told me that, yes, there does seem to be a genetic basis for transgender identity, and they had actually pinpointed some regions of interest. I was surprised. I had assumed that there had not been many genetic studies simply because the argument for transgender issues in public debate almost never brought it up, at least in popular media. So I went ahead and found this on Wikipedia (don’t trust Wiki but this did cite sources so):

A 2008 study compared 112 male-to-female transsexuals (both androphilic and gynephilic), mostly already undergoing hormone treatment, with 258 cisgender male controls. Male-to-female transsexuals were more likely than cisgender males to have a longer version of a receptor gene (longer repetitions of the gene) for the sex hormone androgen or testosterone, which reduced its effectiveness at binding testosterone.[3] The androgen receptor (NR3C4) is activated by the binding of testosterone or dihydrotestosterone, where it plays a critical role in the forming of primary and secondary male sex characteristics. The research suggests reduced androgen and androgen signaling contributes to the female gender identity of male-to-female transsexuals. The authors say that a decrease in testosterone levels in the brain during development might prevent complete masculinization of the brain in male-to-female transsexuals and thereby cause a more feminized brain and a female gender identity.[3][6]

A variant genotype for a gene called CYP17, which acts on the sex hormones pregnenolone and progesterone, has been found to be linked to female-to-male transsexualism but not MtF transsexualism. Most notably, the FtM subjects not only had the variant genotype more frequently, but had an allele distribution equivalent to male controls, unlike the female controls. The paper concluded that the loss of a female-specific CYP17 T -34C allele distribution pattern is associated with FtM transsexualism.[4]

These are only from 1 study each, so I suppose we need to stay skeptical. But what I got from this was that “maleness” and “femaleness” could come from a brain’s exposure to certain hormones during development stages. Certain genetics that prevent the access of hormones to the brain can induce thoughts that, although they are physically one way, their brain is the other. I guess that also brings into question gender fluidity – I once listened to an interview with a trans man who for a while had believed he was a lesbian, then thought he must be genderfluid, before finally admitting that in his mind he was male. But what sort of genetics would a gender fluid person have? I understand people who have neither XY or XX chromosomes – but perhaps there is another factor in there that turns off both the androgen receptor and CYP17 T -34C allele distribution patterns. Perhaps there is something else. That is a different tangent however.

My main point was that transgender people throw into question my beliefs that there is no such thing as male or female brains. I suppose I should have read up more on the effects of our sex hormones on the brain before saying anything. But what does maleness and femaleness mean? There are plenty of men who do not subscribe to gender roles without feeling like they are female. I am proud to be female but I dislike many “feminine” traits. (I also dislike many “masculine” traits though). Listening to the interviews of different transgender people, I tended to hear a few similarities – most people who knew them (and accepted them) reacted with, “oh, right, that makes sense” when they came out as trans. They did not always hate their bodies but they felt uncomfortable in their skin. They never fit in with the other kids of their assigned gender, and when they did, those kids turned out to be LGBT (this was in a more conservative society) or were very liberal people.

Side note: The general argument for transitioning was that the person would come to a point where they had to choose between conforming the brain to the body, or the body to the brain. Most battled for years to conform to their bodies but eventually the brain won out. I think this would make sense for a lot of people who might be against transitioning. It’s just corrective surgery. This makes me wonder if trans people would feel the need to transition if society weren’t so split based on gender. Would they feel comfortable with their bodies if what you looked like didn’t matter? But that is a different topic that is probably best discussed with an actual trans person).

Back on topic – basically, I was wrong. There is, apparently, a difference between male and female brains that isn’t completely based on societal gender roles and our environment growing up. But does it make a difference if this aligns with the gender you are assigned? I’m still not sure I’m convinced. There is still a wide variety among cis-gendered people. If anything, society and culture play a more important role in shaping our brains. Perhaps this difference in environment has had an effect on our biological makeup – some DNA methylation or other that has been passed down for generations that affects the way we think or behave. Even if there was, again, I am not sure if this makes a difference in my initial argument. Only that, now, I agree that there is a “female” and “male” brain (and maybe a “genderfluid” brain?) but this generally has lesser impact on life performance than the environment in which that brain is honed in.

Ah and our bacteria! Our gut microbiota has a direct effect on our brains and the way we think (moods, etc) — what we eat and how we digest it has an effect on our minds! With so many different things affecting the way we think, how much does maleness and femaleness have to do with it? Perhaps, as with anything, it depends on the individual. However, I will still say that males and females are generally capable of the same things. Until proven otherwise. End rant.


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