Ok, to continue with what I was saying. The causes of transexualism are not completely known. This is not an issue that has been studied, extensively. However, recently, there have been studies using MRI's and exploring the limbic system that have demonstrated some potential causality. Both genetics and biology have been considered as links.
Much of the information regarding the studies done on the causes of transsexualism are highly technical in nature. I will attempt to explain them in layman's terms"
A study done in 2000 examined the part of the brain that identifies gender identity...
the central subdivision of the bed-nucleus of the stria terminalis or BSTc for short. They examined the somatostatin (SOM), a hormone, neurons. What they found was this. Males have 3-4 times the amount of SOM neurons than females do. This is regardless of sexual orientation; homosexual males were similar to males just as homosexual females were similar to females. However, when examining the SOM neurons of transsexuals, they found that FTM (females who claimed to be male) SOM neurons were in the MALE range while MTF (males who claimed to be females) SOM neurons were in the FEMALE range. They examined people who had hormone treatment, who had not, who had sex reassignment surgery, and who had not. Didn't matter. The SOM neuron levels remained the same. Also irrelevant was when the individual indicated their transsexualism. This gives indication that whatever the cause, it occurs while the individual develops in the womb.
Link to the actual study and links to other information used:
Male-to-Female Transsexuals Have Female Neuron Numbers in a Limbic Nucleus -- Kruijver et al. 85 (5): 2034 -- Journal of Clinical Endocrinology & Metabolism
Male to Female Transsexual Individuals have Female Neuron Numbers in the Central Subdivision of the Bed Nucleus of the Stria Terminalis - Tara's Transgender Resources
There also may be a DNA link to transsexualism. In a 2008 study, researchers discovered that MTF transsexuals have a longer version of the androgen receptor gene which causes weaker testosterone signals... similar to that of females.
Link to that information:
BBC NEWS | Health | Transsexual gene link identified
The first study that I posted has been reproduced and is being used to explore the answers to a numbers of questions about human sexual development.
If we are talking about biological gender development, we all know that an XX person is female and an XY person is male. However, what this creates is the anatomical differences between males and females. It does NOT impact the brain and hormone level development. It is theorized that in transsexuals, hormone surges, often occurring in the 3rd month of pregnancy occur in the
opposite fashion as would typically occur. An XX fetus might get the hormonal surge, whereas an XY might not. This can account for the differences in the BSTc SOM receptors. There is some discussion that this may be caused by hormones or other medications ingested during pregnancy, such as DES, but there is no conclusive evidence surrounding this. What is clear is that a transsexual's brain-hormonal pathways operate similar to the sex opposite to what they are anatomically.
Things to consider when discussing transsexualism. Firstly, though there is a strong connection between the differentiation in BSTc SOM neurons and gender identity, the mechanisms that create gender are complex and not completely understood; the brain is still a very complicated organ.
Secondly, cases of children who may have had some genital abnormality at birth, and were "reassigned" to the opposite sex for cosmetic reasons at that time, retained their chromosomal identity. In other words, if a boy was born without a penis, but with testicles, and he was castrated a brought up as a girl, he would retain his gender identity and STILL identify as a boy. A study done with children like this found that all eventually presented as male, not female as they were raised. This gives credence to the idea that transsexualism is NOT socially or environmentally driven.
Hopkins research shows nature, not nurture, determines gender
Thirdly, it has been found that true transsexual people cannot be "cured" though psychiatry or psychology. This is NOT a mental disorder, but an inconsistency between brain-hormonal functioning/structure and chromosomal anatomy.
Further links that provided information for this post:
http://www.gires.org.uk/assets/Research-Assets/etiology.pdf
Transsexuality
Transsexualism - Wikipedia, the free encyclopedia
Please feel free to ask any questions. This is just an overview as there is more information.
In my post, tomorrow, I will discuss treatment for GID and how it relates to transsexualism. There is a pretty clear set of guidelines, and as someone who actively treats folks with GID, I will identify them both from a clinical position and from an experiential position.
