Something I’m often asked about is the research done in recent years that point to a biological component to transsexuality.
I get that question both from cisgender (non-transgender) people daring me to present proof that would validate trans identities, and from transsexual and transgender people wanting some understanding of what makes them trans. In both cases, that’s an awful lot to stake on a field of study, and to tackle that, I feel it’s best to present a brief overview, and put that all into a larger context.
I should preface from the beginning that the science currently under study pertains specifically to transsexuals. Other transgender identities (genderqueer, crossdressers, bi-gendered persons) haven’t really been consciously integrated into researchers’ studies at all, thus far, so it is impossible to say if the data proves or disproves anything pertaining to anything but transsexual identities.
“As Nature Made Him”
Dr. John Money famously recounted how an infant was brought to him after a circumcision accident in 1965, whereupon he concluded that the best thing the family could do for the child was to intervene surgically and raise him as a girl. Referred to as “John / Joan” in his writings throughout the 1970s and 80s, Money trumpeted the case study as evidence that gender was entirely socially-constructed and therefore malleable. The reality wasn’t so straightforward.
“John / Joan” had in fact struggled throughout childhood and adolescence, constantly asserting a sense of being a boy, despite the parents’ best efforts to affirm female traits and discourage male ones. Finally, the truth came out, and by the time he met Rolling Stone contributor John Colapinto (who chronicled his story in the book, “As Nature Made Him”), David Reimer had transitioned back to living as male. Unfortunately, Reimer’s story ended tragically in 1994, when a broken marriage, suicide of his twin brother and the loss of all his money in an investment scam drove him to take his own life.
David Reimer’s story woke the medical world to a reality that gender is not so changeable, that biology does indeed play a part in our identities. Opponents of the trans community have sometimes pointed to this as proof that a person can’t change their sex. Reimer’s story, on the other hand, has in fact resonated with transsexuals, who struggle with the same sense of being not the gender that their body indicates.
“Male and Female Created He Them”
There are precedents in nature in which chromosomes, physical sex and / or gender identity have been mismatched. Intersex refers to a large number of conditions in which physical gender variance demonstrably exists (some researchers use the controversial term “Disorders of Sex Development,” but most intersex advocates oppose this terminology as well as the often-accompanying practice of surgically assigning gender at birth). These conditions include: Congenital Adrenal Hyperplasia (in which the adrenal glands in usually female-assigned people produce high amounts of androgens); Androgen Insensitivity Syndrome (in which the body is unresponsive to the effects of testosterone, causing it to develop as female despite being chromosomally male); 5-alpha-reductase-deficiency; Mosaicism and Chimerism; and less obvious conditions such as Klinefelter’s Syndrome or Turner’s Syndrome. It is important to distinguish that intersexuality is not the same as transsexuality. If there is an overlap, it is likely that transsexuality would be a smaller part of intersex phenomena and not the other way around. Consequently, not all people who are intersex experience a sense of being gender variant or transgender in any way.
With these things in mind, researchers began looking at biology for a proverbial smoking gun that would explain transsexualism. What is emerging is a puzzle – it’s not clear yet how the pieces all fit together, but in each of these cases, quantifiable and repeatable patterns have been found.
It’s In the Genes?
Most of the recent press has surrounded genetic findings since 2006. The best publicized has been a finding that an elongated androgen receptor gene has a higher-than-typical occurrence in male-to-female transsexuals. This was not the first study to demonstrate this: many other studies had done so before 2009, but this one had the largest and most quantifiable sample size yet, ruling out random chance and research errors as causes of the findings.
I couldn’t possibly detail all the genetic findings and corroborating studies, other than to say that the volume of study that has accumulated thus far show a likelihood of a chromosomal link to at least some forms of both male-to-female and female-to-male transsexualism. I will, however, list a few relevant links following the article as starting points for anyone interested in delving deeper.
Brain Sex
One of the most controversial areas of research has been a finding in which subtle structural differences were found in the brain development of men and women (which has raised some objections in feminist circles – more later), and the physical structures of transsexuals’ brain development more closely resembled those of their identified genders, rather than their birth sex. Newer studies along this line have replicated this with trans-identified individuals who have not yet started hormone therapy, ruling this out as a cause.
Endocrine Disrupting Chemicals
In 1999, Dr. Scott Kerlin founded a support and advocacy group for male children adversely affected by exposure in utero, to Di-Ethyl Stilbestrol (DES, a synthetic estrogen once administered to pregnant women as a “vitamin” designed to help prevent miscarriage). When DES Sons was only a few months old, a new member raised the issue that he had always felt that he was a girl, and was, in fact, transsexual. This initiated a flood of confessions about other members’ own gender identity issues, and quickly became one of the dominant themes raised by male children of DES births (although not all DES Sons experience transgender leanings). With pharmaceutical companies fearing possible lawsuits, research on DES is underfunded and harder to find than genetic studies or brain sex, but provides a dramatic example of an Endocrine Disrupting Chemical (EDC) that is suspected to influence gender and sex development in the womb.
The EDC theory of transsexuality often speculates that because physical gender and psychological gender develop at different times in early fetal development, the introduction of an interruptive chemical through diet, inhalation, absorption or other methods — usually estrogenic in properties but sometimes androgenic instead — can affect signals sent by the brain during fetal development.
Canadians are probably more familiar with an EDC known as bisphenol A, whose harmful effects resulted in the recall and banning of certain kinds of plastics, sometimes used in the production of baby bottles. Bisphenol A has been shown to have subtle feminizing and cancer-causing effects in animal populations and potential harmful effects to humans, especially young children and infants. The effect on human fetal development is as yet unknown.
Body Maps
Phantom Limb Syndrome has been widely studied to date, but researchers have begun applying this idea to transsexuality, theorizing that transsexuals may in fact have an intuitive knowledge of their body as that of their identified gender, rather than their birth sex. Research here is in its infancy, so I can’t yet point to definitive findings. However, the theory looks solid and promising, is consistent with the body squick that many transsexuals experience (making surgery necessary in order to function in social situations and relationships) and also potentially holds discoveries relevant to other phenomena, including Body Integrity Identity Disorder (BIID, in which a person has an identity in which they are without a particular limb or body part).
It’s Not Infectious… We Hope….
Perhaps the most curious and bizarre discovery has centered around intracellular bacteria referred to as Cytophaga-like organisms (CLOs) - with Wolbachia being the best known. CLOs appear to induce several reproductive effects in its hosts, feminizing male insects. We don’t yet know if CLOs can affect humans in any way: studies haven’t gone that far yet, but it is currently thought unlikely that they can affect organisms so complex as we.
Next: Adding it All Up
It’s important to note that most of the above is an oversimplification. Greater detail can be found in the studies listed with this article… for starters. Next month, I want to look at how all of this relates to trans identities, to feminist thought (i.e. the second wave feminist conceptualization of gender as social construct), to medical ethics, to biological predetermination of human behaviour and most importantly just how much legitimacy should really be staked on biological cause.

Visit this article online for the full list of references.

Mercedes Allen is a writer who blogs at http://dentedbluemercedes.wordpress.com/, has been featured on bilerico.com, PageOneQ and others, and has also developed the website at AlbertaTrans.org as a resource for transgender information and support.