In 2016, a controversial bill was signed in Georgia, banning transgender individuals from using restrooms designated for the sex with which they identify. In the wake of this legislation, Between the (Gender) Lines: The Science of Transgender Identity explored what was known at the time about transgender identity, discussing scientific evidence for its biological bases, as well as the social and psychological ramifications of binary gender classifications. Regrettably, both the text and the figures in this article were being abused by those seeking to support their own beliefs. As such, we decided to remove this article in 2021 to prevent its further misappropriation by individuals and groups seeking to oversimplify this complex subject and promote views that lack a scientific basis.
We still believe in the value of rigorous scientific research about transgender identity and encourage you to read the published, peer-reviewed studies that we cited in the original article if you are interested in learning more about this topic (linked below):
- Transsexuality among twins: Identity concordance, transition, rearing, and orientation
- A sex difference in the human brain and its relation to transsexuality
- Male-to-female transsexuals have female neuron numbers in a limbic nucleus
- A sex difference in the hypothalamic uncinate nucleus: relationship to gender identity
- Changing your sex changes your brain: influence of testosterone and estrogen on adult human brain structure
- Regional gray matter variation in male-to-female transsexualism
- White matter microstructure in female to male transsexuals before cross-sex hormone treatment: A diffusion tensor imaging study
- The (CA)n polymorphism of ERβ gene is associated with FtM Transsexualism
- Should transvestic fetishism be classified in DSM 5? Recommendations from the WPATH consensus process for revision of the diagnosis of transvestic fetishism
We also encourage you to explore additional resources on this topic:
- For a SITN blog article discussing sex determination, check out “I’m XY and I Know It”: Sex determination systems 101
- For a quantitative view of transgenderism in the US, take a look at this analysis from Times Union
- For a review of discrimination against transgender persons, see this report from the National Center for Transgender Equality
- For a more complete discussion on queer acronyms, see this description from BBC news
- For an in-depth look at how disagreements over restroom usage has shaped policy, check out this Politico article
Sincerely,
The SITN editorial team
There are some massive biases and logical fallacies throughout this entire article and it is clearly swung in a political direction rather than a scientific one.
Just a single example off-top – where it is claimed that the variety in BST shows (you’ve worded it pretty conclusively) that transgendered people have some neurological commonality which could be held up something tangibly inherited. You could easily clear this by doing control groups of feminine cis-gendered men and masculine cis-gendered women (since we’re talking self-identification this is just as robust as a trans person’s self-identification conceptually) and eliminating the possibility (the most likely possibility) that in actual fact there is a psychological tendency for women with more masculine brains and men with more feminine brains to elaborate the trans identity as a result of both their natural leanings, nuture in early life and a huge swathe of intersecting elements such as social pressure, desperation, self-worth, loneliness etc.. etc.. rather than that there is any inherent state which can be tied to the physical make-up of the brain.
You could do the same with both the tests mentioned and the one i’ve put forward and find if there’s a degree at which this variation has a critical indication toward transgenderism…
The science is very young – and so far, it all points to a psychological basis and reinforces the idea that there IS biological sex (there is. LOL) and that gender expression can vary as can sexual orientation (though, there is no evidence these things vary independently.).
Hello Ama,
If I understand you correctly, you want controls in the BSTc study. There were controls.
What the researchers thought they’d see was cis homosexual men having similar BSTc to cis heterosexual women. To their surprise they found transsexual women had a BSTc similar to cis heterosexual women. Homosexual men’s BSTc was identical to heterosexual men’s BSTc.
The BSTc size in the transsexual women was not influenced by hormone replacement therapy. In later studies of cis men who received female hormones in the treatment of prostate cancer, their BSTc area was still like the cis men’s. Also, where there was a “phantom limb” syndrome in cis men who had part or all of the penis surgically removed for non-gender reasons, transsexual women who have vaginoplasty reported no “phantom limb” feelings, although they do experience postoperative pain.
I am a 56 year old male, after reading much of this,(replies mostly)..I am happy to see at least people are discussing the “transgender” topic. I personally identify mostly with the Fa’afafine or Berdache type peoples,socially they are being classified as “third-gender”,whether it is transgender labeled or not,really doesn’t matter, I do know ,I have spent a good part of my life surpressing feeling similar, psychological more as a female. I am a fairly practical type/rational type,and not wealthy,yet even if I had the money,I would not select any type of surgery or “hrt”,yet I have much empathy for those whom do, I consider myself pan-sexually, I must no matter what,be in the “traditional feminine role” or in gay terms “bottom”,I am normally attracted to “straight males ” yet again,I identify as pan-sexually, and try to live by open-mindness. The contrast of the two words, that is Transgender verse Transexual is very clear,Transexual very defined,yet transgender,very vague and unclear,I do know I have been personally am evolving psychological toward my “Feminine Role”,I have been celibate for about 12 years,yet very much desire sex,yet feeling “feminine” is more important,embracing it,nuturing my femininity. I very much know Society is slow to change,takes generations,thus I just have to be “as I feel “,I have waited all my Life for Society to change,very little has!,Yet I think it important to keep this Topic Alive,..if we don’t change as a whole whether this topic,or so many others related to accepting others as they are(as long as not harmful,and transgender is not), We are not evolving as a society, if we can’t get beyond this ,so I say go to work,try to be your best,and be whatever degree of Transgender,Third-gender etc, you need to be..what is normal by society standards,don’t mean it is Right!…was Slavery!
If it’s an obsessive behaviour, then it’s one that tends to occur before people have an idea about race or disability. Typically first appearing at around the age of 3-4 when most children start to develop a concrete idea of their own gender. Certainly well before most mental illnesses/disorders could hope to be diagnosed. However, these children are clear, consistent, and persistent in their assertion about their gender.
This is outside the various physical findings that have been outlined in the links in the original article – such as small brain structures that are sexually dimorphic showing features of the gender that is being expressed rather than the gender that was assigned.
As for why we talk about assigned gender at birth, is that even while the birth certificate says sex. The truth is that babies are not raised in a vacuum. Everything from their Name to the colour of their clothes is gendered. The way that they’re treated is gendered, as are the toys that they are given to play with. All of this comes down to the single letter that is placed on their birth certificate. Prior to around 3-4, a childs gender doesn’t actually mean anything to them, so it’s all down to the way that the adults treat them. Thus assigned. The fact that up to around 2% of the population are transgender, most estimates put them at around 1%, and I’ve seen articles suggesting that it could be as common as intersexuality (in the case of intersex children it is most definitely assigned at birth).
When a little girl acts like a girl, few she’s obsessive. We find that perfectly fine. However, when someone adults want to behave like a boy starts to insist on behaving in the girl way, we haul out the word obsessive.
I disagree with the notion that items adult gender as boy items or girl items are seen in the same way by children. Trans kids are drawn to the peer group with which they identify and upon arrival use the items that are available and part of the girl-child culture or boy-child culture. When children seek out gender “opposite” items, they are signalling to adults where the child’s identity lies.
I disagree with your statement, “Prior to around 3-4, a childs gender doesn’t actually mean anything to them.” In fact it means a great deal to us and as many a parent finds out the hard way, the trans child will not be turned aside and will transition.
“Before most infants are named, they are assigned a sex based on the appearance of their external genitalia by a third party.”
Nope. The above statement is a polemic, not a fact. Here’s the fact. It is a reasonable assumption on the part of any rational person that a child’s eventual subjective view of their gender will match that of their genitalia for the simple reason that, for all but .035 % of the population, that is the case. Darkly hinting that there are oppressive forces at work dictating gender by illegitimately imposing a prejudice is just plain nonsense and is exactly the sort of identity politics hyperbole that discredits attempts to protect people from discrimination and other types of mistreatment at the hands of intolerant people.
Whatever the scientific basis, biological or psychological, of transgenderism turns out to be, assuming we are ever able to even make a such definitive analysis, there are no such oppressive forces at work. It may well be that there is a biological basis for transgender. We simply don’t yet know. On the evidence, it could just as well be a form of obsessive behaviour. People like Rachel Dolezal, who believes she’s a black person trapped in a white person’s body; or the so-called “transabled”, people who believe they are a disabled person trapped in an “abled” person’s body, and who have in some cases disfigured and harmed themselves in order to become “disabled” are clear examples of obsessions not based in reality. On the surface at least, the beliefs of such people are convincing analogues to the convictions of transgender people and suggest that there are equally reasonable possible alternative explanations for those convictions. But whatever the scientific consensus eventually is, can we please stop talking about people ominously being “assigned” gender at birth by “third parties”. That is a false and pernicious narrative.
“0.035%”
No. 0.6% of people are transgender. More than 1% are intersex. This is MORE THAN 50 times as common as you claimed.
As for biology:
Endocrine Practice. 2015 Feb;21(2):199-204. doi: 10.4158/EP14351.RA.
Evidence supporting the biologic nature of gender identity.
Saraswat A, Weinand JD, Safer JD.
Abstract
OBJECTIVE: To review current literature that supports a biologic basis of gender identity.
METHODS: A traditional literature review.
RESULTS: Evidence that there is a biologic basis for gender identity primarily involves (1) data on gender identity in patients with disorders of sex development (DSDs, also known as differences of sex development) along with (2) neuroanatomical differences associated with gender identity.
CONCLUSIONS: Although the mechanisms remain to be determined, there is strong support in the literature for a biologic basis of gender identity.
Lastly,
“Gender incongruence, meanwhile, has also been moved out of mental disorders in the ICD, into sexual health conditions. The rationale being that while evidence is now clear that it is not a mental disorder, and indeed classifying it in this can cause enormous stigma for people who are transgender, there remain significant health care needs that can best be met if the condition is coded under the ICD.”
– from the World Health Organization announcement of the release of the ICD-11 update
Scott, when you make concessions like, “It may well be that there is a biological basis for transgender” you negate what is real, biologically certain (apart from hermaphroditism, which we know is a rare disease) and normal in human history. Of course the abnormality is sad in its very low prevalence and incidence, and any reasons for this biological deviance that the medical and scientific world may find – genetic, environmental, medicative – would be helpful. But for the 99% of biologically normal people (assuming a disputed range for the incidence of hermaphroditism), there can be no doubt that at birth of a human being, we have either a male or a female. Thereafter, if someone wants to say or do something contrary to what their physical bodies show their sex to be, they do it in the wisdom of their own eyes and mind. No one can argue biological reality away, nor “research” gender identity into the body of a normal human being, which is opposite to his or her physical sex.
“normal in human history”
You seem to be shaky on this part.
There are 37 current cultures with words for 3rd gender and many with 4th and 5th genders. Past cultures increase that number to many more.
The 99% number you assign may be invalid in these other cultures as they adjusted gender for various types of penises or vaginas
The issue here is that culture has a part in defining gender and you are only barely correct on the genitalia statistics. The incidence of micro penis, extra long exposed clitoral glans, enlarged labia are beyond the 99% you try to claim for ‘normality’.
The clitoris is as large as any penis. The clitoris is only now being properly shown in texts. Both organs derive from the same starting proto-organ. The clitoris actually fills the area surrounding the vagina and it’s crus extends to either side of the vagina walls. It’s cavernosum flesh is responsible for the swelling around the vagina and upward swell of the labia. The medical diagrams in doctors’ offices that are dated as late as 2008 show a women with an incredibly abnormal, micro clitoris.
So then what about gay men who are extremely feminine and lesbian women who are extremely masculine? These brain chemicals surely affect them as well, right? Or Androgynous people whole look both male and female at the same time. You can’t limit this to JUST transgender people. You failed to mention how many people were studies to get these “findings”. The article I read prior to this, studies were don on 6 mtf transgender women who were all deceased. Have live people been studied? How many? There are so many more questions and studies to be done to have a definitive answer. These are all theories and suggestions at this point. Nothing factual that says YES this IS what’s happening
A transgender person isn’t just a more masculine woman or a more feminine man. In the same way that you know what gender you are, transgender people know what gender they are.
Think about it like sexuality except with gender instead. No one can explain why they are attracted to the people they are, just that they are. In the same way we can’t tell you why we are transgender, just that we are. Gender non-conforming people are not transgender, they just make you uncomfortable because they don’t fit into your idea of what a man or woman should do or how they should dress.
You slid right over the point on androgynous, those that gender test as 50-55% male and 50-55% female. If they feel they are two-spirits or have no gender, that would be a gender identity not matching their birth genitalia (assuming not intersex/hermaphrodite) and by definition; they are transgender people.
Male/female are not the complete Venn diagram of gender identity since gender is rooted in culture and past cultures have had 3rd gender words for thousands of years; many that still survive.
I’m aware of the fact that I didn’t explicitly cover any of the non-binary Transgender identities, but that’s because they are a transgender identity, just not a binary one. Even a genderfluid person can tell you that they’re genderfluid even if they don’t know the words that we’d use.
Also, at the top of the article they’ve got a chart of gender identities, granted it doesn’t include agender, but that’s because trying to plot a null value on a chart just doesn’t work.
Finally, AFAIK androgynous is an appearance, not a gender identity. Remember, being transgender is about how your gender identity relates to that assigned to you at birth, not your gender expression.
My question is centered around identical twins. Why do you believe that identical twin DNA is identical? Sure they look alike and typically have similar phenotypes. But even during embryo development, mutations can arise. DNA won’t translate identically. There are factors, even in the womb, that will preclude identical DNA between the twins. Although subject to the same environment, that does not ensure 100% identical DNA, nor 100% identical mutations. There are also epigenetic factors to consider (processed food, plastic containers, GMO foods, cell phones, electrical lines, chemicals in general, etc.) that could cause genetic mutations. The etiology of this condition is not well understood. We should dig in and search out a root cause instead of accepting this as nature.
Thanks for your question! Identical twins, as defined in these studies, are monozygotic — meaning that the initially come from the same fertilized egg that at an early stage splits to eventually make two embryos. You’re correct that identical twins can have some small differences in their DNA — this happens in the same way that any given person does not have 100% exactly the same DNA in all of their body: sometimes when cells are dividing, a non-lethal, non-cancerous mutation is made, and that mutation is passed onto all the other cells that end up being made as a result of division of that mutated cell. That being said, identical twins have very, very similar DNA in most of their bodies — much more similar than fraternal twins or siblings, and this comparison to fraternal twins is what really matters for these studies. This means that if a study finds that identical twins are more likely to share a trait than fraternal twins, there is likely to be a genetic component because identical twin DNA is MORE similar than fraternal twin DNA– you can read more about this logic here: https://en.wikipedia.org/wiki/Twin_study
The idea is actually that identical twins have very (almost 100%) similar DNA, but are exposed to DIFFERENT environments. So if the trait is entirely environmental, identical twins will not be more likely to share it than fraternal twins. So any of those epigenetic differences caused by environmental factors that you’re mentioning (which actually don’t cause mutations in DNA, just changes in which genes are on or off) would be considered as coming from environmental influence not from genetic conditions.
No one is saying transgender identity is 100% caused by DNA mutations (if it were, then every set of identical twins would either both be transgender or both not be transgender) — just that there is likely some influence of genetics because two identical twins are more likely to share gender identity than two fraternal twins.
One of the theories referenced above is that where intersex individuals are caused by a hormone variance at one stage in pregnancy, trans individuals are caused by a similar thing at a different stage in pregnancy.
Thanks for the article. 2 questions:
1. It’s mentioned that identical twins have ‘almost 100%’ similar DNA, however, don’t all humans have nearly ‘almost 100%’ similar DNA? The delta between individual humans (twins or otherwise) is on average 0.1%. Is there an exact figure to quantify the similarity of the DNA among twins used in the study?
http://humanorigins.si.edu/evidence/genetics
2. The study uses 112 people and is somewhat biased toward those willing to volunteer. This seems like an extremely small sample size to determine any conclusions with statistical significance. Is there really much that research can tell us about any test group based on 112 examples?
This is for those who refuse to accept multiple genders, claiming that there is only male and female. Apparently you are unaware that there are those who are born hermaphrodite, meaning both sexes. In more modern times, if by chance an individual is born with both sexes, the doctor analyzes which sex they carry more physical organs with, and chooses which sex organ to remove. The issue is, sometimes an individual is born with some internal sex organs of both sexes. I have a friend who is now in their sixties and born hermaphrodite. As an infant, the doctor and parents decided that this person would be male. Yet, they left this person with the female and male internal organs, i.e. ovaries. The result is that they experienced both female and male puberty. At the time of puberty, they learned that they were born hermaphrodite. This individual, who is still physically male, even went through female menopause. So, for those of you who say that there is only two sexes, I suggest doing your research. Even physically, there are those born outside of the male and female binary.
No, I think all are very aware of this physical anomaly; it’s rare, and really abnormal, of course not a condition easily managed, physically and emotionally.
They’re called intersex these days rather than hermaphrodites. And their development is studied as much if not more than transgender people are.
They also often go through similar things to transgender people
There is just so much pseudo-science in this “article”! Shame on Harvard! Yes, transgender is INDEED a mental disorder. It is the result of a neurological defect due to hormonal abnormalities that occurred during gestation. The BRAIN is at fault here.
And the “similar” structures theory of the brain is such a cop-out. No, you CANNOT just take an unknown brain and determine if it came from a man or a woman without taking a DNA test. It is not possible.
Also, the very idea of there being multiple genders is absurd. It is a biological impossibility! Humans have TWO parents, not three or four! TWO! Gender is strictly binary! If someone has a chromosomal abnormality that results in anything other than XX or XY they are INFERTILE and suffering from many genetic defects! These conditions do not counter the fact that gender is indeed a binary. There is only MAN and WOMAN, no other!
I’m sick of science becoming polluted with politics Stick with the FACTS and leave the feelings elsewhere! Science should never be agenda driven, and yet here we are!
@ Ted Teddison To be entirely honest you are a very very confused boy, and to be frank I’m uncertain whether you be contrarian or cretin, but I totally have no care about that.
FACT is humans have been switching genders for centuries. They call them cross dressers. There’s a colloquialism for it: GENDER BENDER. Cross dressers pop on a dress, slap on some makeup, and adopt female mannerisms thereby blurring or changing ” the individual’s and society’s perceptions of (their) sexual identity”.
What defines a gender?
The World Health Organization states, “‘[s]ex’ refers to the biological and physiological characteristics that define men and women,” and “‘gender’ refers to the socially constructed roles, behaviours, activities, and attributes that a given society considers appropriate for men and women.”
Just chucking on a frock and some lippy doesn’t alter their biological and physiological characteristics.
Now, on the other hand a Trans person generally requires drugs and/or surgery to permanently change their biological and physiological characteristics to adopt a new sexual identity.
Therein is the subtle differences between a trans person and a cross dresser.
The other subtle difference is intent. A cross dresser does so as a temporary gender swap before reverting back to their natural birth sex. A trans person chooses to not revert back.
Now.if you’re still confused l guess we need to drag out the crayons and I’ll try to stick to simple single syllable words for you.
Lol, someone’s butt hurt over facts
I identified myself as male before I recognised my assigned sex is female. I had no idea why my body is like that. Of course before I knew there is a thing like cross-hormonal therapy or sex reassignment surgery, I was in a mindset that accepted this lack of external appearance of my body. Since I knew there is a thing called hormone replacement therapy, my mindset was changed. I had an urge to change the way I look. I was looking forward to the day I can start HRT. I became more and more depressed and vulnerable, isolated and sad for a long time. I was born and had been living in a developing country of South East Asia, there I had to hide and manipulated people that it was just my personality, not to let them know I’m transgender. I moved to Australia two years ago, with the very different better-organised society, my depression somehow declined dramatically although I still have to manipulate people who I am.
There are little known about transgender, scientifically. Now I’m studying. I’ll get involved in science and medicine, finding the reason behind this mystery.
But I believe, speaking of what transgender really means, it is like we’re seeking the answer for why humans can do such amazing things.
Hardly would science disagree. Science means that which objectively can be validated again and again, in a laboratory under the same controlled conditions – so the study mentioned in my comment above on 26 Nov. No so the “pinknews” study you refer to. Now the insula of the brains of cisgender and transgender differ. Really! Don’t the brains of all people differ. The insula has been hardly studied – it’s still a mystery. As with this study, you can’t compare the brains of adults to make some subjective finding and then transfer this finding to babies in the womb and claim it as an objective scientific finding. That’s pseudo science at its best.
The study suggests that someone may be “trans” in the womb. This is clutching at straws. The same would then apply to paedophiles or psychopaths. They are born like that? So we all have the freedom to choose what we were born as – trans, paedophiles, murderers, etc. Nice!
Take now the insula of the brain – subject of the “pinknews” study. Scientists tell us it deals with self-awareness, emotions, morals, etc. Now we KNOW that as we grow, develop, learn, experience, etc, we adopt certain behaviours. This is quite simple to understand, and experience. A trans-person is NOT born like that (neither a paedophile), because true science cannot prove this. The person is born male or female (genetically, science proves this categorically, again, and again). But learned behaviour, exposure, influence, environmental factors, and so on shape and mould the person. This learning and appropriation is generated, recorded, stored in the brain – in the insula, for example. Of course the insula of one person shaped trans-gender through conscious learning will differ from a non-trans person. Really, this is not difficult to grasp. So the researchers of the “pinknews” study vaguely assert that they are “led to believe” and to “suggest.”
Brain scans in studies show that the insula lights up when people crave things, feel pain, empathize, etc. So it develops and responds as we live and grow. When paedophiles were studied, their insulas lighted up when pictures of babies were shown them. This is learned behaviour, same with trans people.
Take animals. They also have an insula, and we know that they have emotions and adopt learned behaviour. They’re not humans of course, but still, do they struggle with gender identity?
There are thousands of studies available claiming scientific proof for transgenderism. You may quote them all, but every one fails when exposed to true, objective, repeatable scientific studies. God made no mistake when He created them, male and female.