On the Science of Changing Sex

Gender Allusions

Posted in Brain Sex, Science Criticism by Kay Brown on February 24, 2015

critical-thinkingIs “Gender Identity” biological?  For most people, the answer is intuitively obvious, “duh!”.  Of course, for these people, they usually also insist that the markers for such identity is some privileged and testable characteristic, like genitalia, which is easy to observe, or karyotype (sex chromosome configuration) which requires a microscope.  But for people with Disorders of Sexual Development (DSD), these markers may not be all that clear.  Further, what are we to make of the gender identities of transsexual and transgendered people, people whose experienced / stated gender identity is at odds with all currently known sex markers?  IS there a biological etiology?  And is that etiology the same as that that gives rise to the gender identity of non-trans people? A recent review article attempts to answer these very questions.  Sadly, I believe that it falls far short of a conclusive answer.  In fact, as I will show, it invokes conclusions from several papers as evidence that are quite questionable.  Further, the authors failed to note the very probable multiple etiologies for Gender Dysphoria and their associated gender identity resolutions suggested by the Freund/Blanchard two type taxonomy of MTF transsexuality. First, they reviewed evidence for a biological basis for the phenomenological existence of “gender identity” in non-transfolk which comes from those with certain DSDs,

A seminal study by Meyer-Bahlburg et al involving outcomes of XY individuals raised as females due to severe non-hormonal, anatomic abnormalities of sex development has provided the most convincing evidence that gender identity is fixed. These congenital abnormalities include penile agenesis, cloacal exstrophy, and penile ablation. For many years, female gender assignment along with surgical feminization was the dominant approach for these patients. In this study, it was observed that 78% of all female-assigned 46 XY patients were living as females. While the majority of these patients did not initiate a gender change to male, none of the 15 male raised 46 XY patients initiated a gender change to female. Thus, risk of questioning gender identity was higher in those patients raised as females than in those raised as males among 46 XY subjects with one of these conditions. A study by the same group that examined the degree of satisfaction with surgical intervention reported by patients with 46 XY genotype also found that those subjects raised as boys were considerably more comfortable with their gender identity. – Another seminal study relevant to this topic was by Reiner and Gearhart in their review of 16 XY genotype subjects with cloacal exstrophy who underwent female gender reassignment surgery. Out of the 14 individuals raised as girls, 4 announced they were male and 4 later chose to live as boys when they became aware of their genotype. The 2 individuals who were raised as males identified as males throughout life. The sexual behavior and attitudes of all 16 subjects ultimately reflected strong masculine characteristics regardless of gender assignment. Thus, children who were born genetically and hormonally male identified as males despite being raised as females and undergoing feminizing genitoplasty at birth. Although cohort size in these studies is small, these data provide the strongest evidence for biological underpinnings of gender identity.  …  In a study of affected subjects, gender role changes were reported in 56-63% of cases with 5 alpha-reductase-2 and 39-64% of cases with 17-beta-hydroxy-steroid dehydrogenase-3 who were raised as girls (6). These data support the concept that gender identity might be attributed to hormone milieu during intrauterine development on some occasions.

These studies are indeed very strong evidence.  Looking at the data, we see that of those raised as girls, 22% of of these subjects in the first study and 57% in the second study, while in the third study, those with hormonal abnormalities, 56-63%, chose to socially transition from female-to-male.  Compare that to the very, very small number of 46XX individuals in the general population who experience severe gender dysphoria and choose to transition.  As an aside, the fact that not all chose to transition should not be taken as proof that gender identity is all that malleable, but should probably be taken as a demonstration that social transition has very high social costs and is not undertaken lightly. Strangely, this paper did not explicitly mention that the majority of these individuals, whether they experienced gender dysphoria or not, were exclusively gynephilic, but they did allude to it.  Also puzzling was their failure to include the converse situation of individuals with 46XY and complete androgen insensitivity syndrome (CAIS), all raised as female, who are extremely unlikely to experience gender dysphoria or sex reassignment, and are universally exclusively androphilic.  Or the even more interesting case of 46XX progestin influenced females raised as male, 50% of whom transitioned from male to female and all are exclusively androphilic.

Thus, they failed to explicitly show the very high correlation of brain sex with gender identity, gendered behavior, and sexual orientation. Having shown that there is indeed very strong evidence that “gender identity might be attributed to hormone milieu during intrauterine development on some occasions”, which supports the notion that gender identity has a basis in biology (as opposed to being purely a social construct overlain on observable sex differences), it is tempting to say that transsexuality, all transsexuality and transgender identity, is also the result of mismatched hormonal milieu.  In fact, many transsexuals hold to just such a position.

But they would be dead wrong.

The logical leap that all transsexuals have such an etiology is not supported by the above evidence.  In fact, given the very probable differing etiologies for Gender Dysphoria and their associated gender identity resolutions suggested by the Freund/Blanchard two type taxonomy of MTF transsexuality, at least one of these types must NOT have been caused by such.  Blanchard went on to predict that this would be born out by studies of the sexually dimorphic structures in the brain, predicting that the exclusively androphilic MTF transsexual would show shifts toward the female morphology, while the other type would not. It is here that this recent paper has its biggest failings, in that not only did they not discuss this issue, but included very problematic studies by Swaab that purported to have shown female like shifts in non-exclusively androphilic transwomen.  These papers did show the shifts in the BSTc and INAH3, but incorrectly concluded that they had existed prior to exogenous HRT and incorrectly concluded that these features in the brain were organization effects of endogenous hormones in utero, when the data clearly demonstrated the opposite, that these shifts were purely activational effects from exogenous estrogenic and anti-androgenic HRT.  To be fair, they did mention that the BSTc was potentially questionable, but completely failed with regards to the INAH3, which demonstrably is not evidence for a biological basis of gender identity.

In reviewing the recent grey and white matter studies, they failed to note that it fits and supports Blanchard’s prediction, which had they done so, would have strengthened their argument for a biological basis for a conventional gender identity in exclusively androphilic MTF transsexuals.  That is to say, that they experience the same feminine “gender identity” as females because their brains are female like.  Conversely, they would also have evidence for a biological underpinning to autogynephiles sexuality, a non-sexually-dimporphic one, which lead to an epiphenomically generated “female gender identity” later in adulthood.  (See my essay on the different origins of cross-gender identity in transsexuals.)

The authors reviewed the literature on possible genetic factors that could lead to transsexuality, noting that they were inconclusive. Totally absent in this paper was any mention of the papers that document the fraternal birth order effect found in exclusively androphilic MTF transsexuals. All in all, I was disappointed in this paper.

I found it shallow, lacking in both depth and breadth, and literally out of step with much of the literature on the cutting edge of the science.

(Addendum 7/7/2015:  I got suspicious of this paper as it reads like a cherry-picked list of papers that support the brain sex hypothesis for all transsexuals, including “late onset” transwomen, so I checked into the background of the authors.  Sure enough, one of the authors is transgendered.  While that alone is NOT damning (after all, so am I), it does explain why this paper only referenced the studies it did, and did not include those studies that when considered as a whole, would show that while one subset of the larger transsexual population could possibly be explained by the brain sex hypothesis, most transwomen could not.  This paper then can and should be considered part of the ongoing effort by some in the transgender community to deny the evidence of the two type taxonomy.)


Aruna Saraswat, MD, Jamie D. Weinand, BA, BS; Joshua D. Safer, MD, “Evidence Supporting the Biological Basis of Gender Identity” (2015) DOI:10.4158/EP14351.RA

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Shades of Grey…

Posted in Brain Sex, Confirming Two Type Taxonomy, Female-to-Male by Kay Brown on February 23, 2015

shrinking brainShades of Grey… Matter

We live in exciting times – At least scientifically.  We can now peer into the heads of transsexuals to see if their brains exhibit sexually dimorphic features that match their natal sex or their preferred gender.  Years ago, Ray Blanchard made a prediction, based on early evidence that there was a taxonic difference between “homosexual” and “non-homosexual” transwomen in sexuality, natural gendered mannerisms, age of transition, etc, that the former would show sexually dimorphic features in the brain that were shifted in the female direction while the latter would not, but would show features that were different than controls, but that they would not be sexually dimorphic features, and definitely not shifted in the female direction.  We now have yet more evidence that that prediction is correct, giving more weight to the two type taxonomy of MTF transsexuality, namely exclusively androphilic vs. autogynephilic.

The best evidence would be to use two populations of transwomen, one known to be exclusively androphilic and the other not, and test them for the same features, using the same type of measurement.  We now have that data for grey matter distribution in the brains of both types of transsexual.

In the earlier Savic and Arver paper, they compared grey matter distribution of 24 gynephilic transwomen, before HRT to that of heterosexual men and women.  (Remember, HRT itself causes a shift in sexually dimorphic features due to activational effects of sex hormones, and the lack of such hormones.)  The conclusion?

“The present data do not support the notion that brains of (gynephilic) MtF-TR are feminized.”

In the later Simon paper, they compared grey matter distribution of 10 exclusively androphilic transwomen, and 7 exclusively gynephilic FtM transmen, before HRT to that of heterosexual men and women.  The conclusion?

“Our findings support the notion that structural differences exist between subjects with GID and controls from the same biological gender. We found that transsexual subjects did not differ significantly from controls sharing their gender identity but were different from those sharing their biological gender in their regional GM volume of several brain areas, including the left and right precentral gyri, the left postcentral gyrus (including the somatosensory cortex and the primary motor cortex), the left posterior cingulate, precueneus and calcarinus, the right cuneus, the right fusiform, lingual, middle and inferior occipital, and inferior temporal gyri. Additionaly, we also found areas in the cerebellum and in the left angular gyrus and left inferior parietal lobule that showed significant structural difference between transgender subjects and controls, independent from their biological gender.”

The choice to explore only “homosexual” transsexuals in this study was informed by the researchers’ knowledge of the Freund/Blanchard taxonomy and of Blanchard’s prediction, as they explained,

“Both MTF and FTM patients were eligible for the study, but only those with homosexual orientation. The rationale for this choice was based on the Blanchard typology which considers two fundamentally different types of transsexualism: homosexual and nonhomosexual. Homosexual transsexual individuals are sexually attracted to the same biological gender, while nonhomosexual transsexual individuals are attracted to either the opposite gender or show no sexual orientation/attraction at all. According to Blanchard, homosexual transsexuals are usually younger at initial presentation of gender identity disorder and show more pronounced and frequent childhood femininity, as well as different anthropometric data. One might argue that mixing individuals from both transsexual groups in one study targeting the neurobiological background of transsexualism might bias the results by introducing heterogeneity in the sample. Thus, in our study, only homosexual transsexual individuals were included preventing our findings from the aforementioned bias.”

This points to growing recognition within the scientific community that the two type taxonomy is correct.  They went further, indirectly referring to the taxonomy and Blanchard’s prediction,

“In another study also limited to MTF transsexuals Savic and Arver, reported no “feminization” of any brain region with regard to structure. Nonetheless, certain brain areas (clusters ≥100 voxels) showed characteristic structural features in the transsexual group compared with both male and female control groups. Specifically, they found reduced thalamus and putamen volumes and increased GM volumes in the insular and inferior frontal cortex and in the right temporo-parietal junction (angular gyrus and superior temporal gyrus) in the transsexual group compared with both control groups. In our study, however only the angular gyrus (but in the left hemisphere) was affected among these areas, showing lower regional GM concentration in both FTM and MTF transgender subjects compared to controls, independent of their biological gender. When comparing the results reported by Savic and Arver to either our study or to other imaging studies in the literature of transsexualism, it has to be taken into consideration that their reported results were obtained from a solely nonhomosexual transsexual group of patients. The lack of real overlap between our and Savic and Arvers’ findings, despite the very similar methodology used, might at least in part be explained by the difference of the sexual orientation of the two samples.”

Truly, exiting times.


Ivanka Savic, Stefan Arver, “Sex Dimorphism of the Brain in Male-to-Female Transsexuals”

Lajos Simon, Lajos R. Kozák, Viktória Simon, Pál Czobor, Zsolt Unoka, Ádám Szabó, Gábor Csukly, “Regional Grey Matter Structure Differences between Transsexuals and Healthy Controls—A Voxel Based Morphometry Study”

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Child’s Play

Posted in Female-to-Male, Science Criticism by Kay Brown on February 9, 2015

critical-thinkingFor years, critics of transkids’ identities have made claims that transkids are either “confused”, “delayed”, or “pretending”.  Many papers describing feminine boys from the 1960’s would describe them as being “talented mimics”, explicitely taking the position that men and women, boys and girls, do in fact have in-born differences in behavior, mannerisms, and motor-movements, but that these feminine boys were NOT exhibiting natural behavior, but were consciously, or “subconsciously”, observing girls and women, and learning to “mimic” these behaviors.  Of course, those of us who were such and grew up to transition, have long begged to differ!

Today, we have a published paper that demolishes these notions.  At the core of the paper is the ability to determine implicit associations between concepts.  If you are not familiar with this tool, it may be useful to review the Wiki page on Implicit Association Testing .  One of it strengths is that it cannot be “faked”.  It is impervious to Social Desirability Bias or other impression management distortions.  It is also impossible for someone to be “pretending”, as the cognitive load to evaluate the test set-up, determine the “right” answer, etc. would create an obvious delay in the test.  Further, if a child were “confused” as to the meaning of sex and gender, there would be an obvious anomalous signature in the test results.

ImplicitThe study involved 32 transkids, ages 5-12, 12 FtM, 20 MTF, who have already transitioned full time, with the full support of their families.  This would obviously include “early onset” transkids.  However, and this is critical, we know, or at least suspect, that some of these kids will “desist” being gender dysphoric before puberty, if they follow the trend already seen in other studies, most especially the Steensma study from the Netherlands.  Yet, for all of that, the results of the study show that these kids are completely consistent in their implicit gender identity and preferences as their opposite sex, non-trans, controls and siblings.  They are NOT pretending, nor confused.

The folks who conducted this recent study are continuing their work, looking at these kids as they grow up.  They are looking for additional transkids to join the study.

Study on Gender Nonconformity in Children

Hi from the TransYouth Project at the University of Washington! We are researchers interested in gender development in children and have a new research project we are currently recruiting families for. The project aims to better understand gender development in gender nonconforming and transgender children.  Our new study takes 30-60 minutes and includes children ages 3-12. We are running the study all over the U.S. and Canada so please let us know if you are interested and we can let you know when we’ll be in your area. We are hoping to recruit gender nonconforming children as well as their siblings (where applicable). All data collected as part of this study are confidential. Payment is $10 per parent and $10 plus a small toy per child. There is an optional longitudinal component that we can tell you more about as well if you are interested. To sign up for the study, please visit: http://www.transyouthproject.org. If you have any questions, feel free to contact me, Dr. Kristina Olson, via email (krolson@uw.edu) or phone (206-616-1371). Thanks for considering being a part of this research or telling someone who might be!


Kristina R. Olson, Aidan C. Key, Nicholas R. Eaton, “Gender Cognition in Transgender Children“, Psychological Science

Thomas D. Steensma, Roeline Biemond, Fijgie de Boer and Peggy T. Cohen-Kettenis, “Desisting and persisting gender dysphoria after childhood: A qualitative follow-up study”

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