Firstly thank you Penny for the interest you showed in my article. I was at one point uncertain whether to submit the adult revamped version or the simpler, juvenile version I first wrote at 16.

Many transsexuals, therapists, human sexuality researchers, religious liberals, and others believe that transsexuality is determined before birth. Some believe that it is determined by one's DNA at conception. others hold to the theory that it is caused by irregular levels of sex hormones to which the fetus may be subjected. These beliefs are grounded in research into genes and traits of transsexuals.

Is transsexualism genetically determined?

As noted elsewhere in this section a transsexual is a person who experiences Gender Identity Disorder (a.k.a. Gender Dysphoria), Their genetic gender is different from their perceived gender. Some describe themselves as a woman trapped in a man's body, or vice versa.

This disorder is rare. It generally causes serious personal conflicts and depression, often starting in pre-school children. Their level of frustration and anxiety is often so high that many become suicidally depressed. The rate of completed suicide for transsexuals was once believed to be about 50% by age 30. Since then, sex reassignment surgery (SRS) has become more widely accessible. Many transsexuals can now have their physical appearance modified to make them appear more like the gender that they feel they are. This surgery has been shown to be generally effective, and the suicide rate among transsexuals has apparently been greatly reduced.

Religious conservatives generally believe that transsexuality is a chosen lifestyle to which a person can become addicted. The solution is therapy and prayer.

The opinion of some gays, lesbians, and bisexuals towards the causes of transsexuality may be influenced by a desire to support their belief that sexual orientation is similarly genetically determined.

Australian DNA study during 2008:

Australian researcher Professor Vincent Harley has led an Australian-American study of transsexuality. He acknowledges that the cause(s) of transsexuality have been debated for years. He said:
"There is a social stigma that transsexualism is simply a lifestyle choice. However our findings support a biological basis of how gender identity develops."

He was the lead researcher in the an Australian-American genetic study of transsexuals -- the largest to date. Included were several research groups in Melbourne Australia and in the University of California in Los Angeles (UCLA). It was funded by the National Health and Medical Research Council in Australia, and the National Institutes of Health in the U.S.

They compared DNA from 112 MTF (male-to-female) transsexuals with DNA from 250 males who did not experience gender dysphoria. Results of the study were published in the 2008-OCT-27 edition of the journal Biological Psychiatry.

The researchers found that the transsexual subjects were more likely to have a longer version of the androgen receptor gene in their DNA.

Lauren Hare, a researcher at Prince Henry's Institute said:

"We think these genetic differences might reduce testosterone action and under-masculinize the brain during fetal development."

"Studies in cells show the longer version of the androgen receptor gene works less efficiently at communicating the testosterone message to cells. Based on these studies, we speculate the longer version may also work less efficiently in the brain."

Terry Reed from the Gender Identity Research and Education Society said:

"This study appears to reinforce earlier studies which have indicated that, in some trans people, there may be a genetic trigger to the development of an atypical gender identity."

"However, it may be just one of several routes and, although it seems extremely likely that a biological element will always be present in the aetiology of transsexualism, it's unlikely that developmental pathways will be the same in all individuals."

Researcher Trudy Kennedy, director of the Monash Gender Dysphoria Clinic, said the study supported previous evidence that genetics and brain gender were important in transsexuality. She said:

"This is something that people are born with and it's certainly not a lifestyle choice as some have suggested."


Studies of fingerprints, left handedness, and ancestry of transsexuals:

During 2000-JUL, Professor Richard Green, visiting professor of psychiatry at Imperial College in London, UK discussed transsexuality at the annual meeting of the Royal College of Psychiatrists. His presentation was based on a study of 400 male-to-female (MTF) and 100 female-to-male (FTM) transsexuals in the late 1990s at the gender identity clinic in Charing Cross Hospital in London. His group determined that:


Over 50% of transsexuals are left-handed -- many times that of the general population.
Transsexuals had distinctive styles of ridged finger prints, and
Transsexuals had more aunts than uncles on their mother's side.
Male transexuals had more older brothers than average.

handy link http://www.gires.org.uk/

And some more, I don't pretend to understand it all, but get the gist,, Perhaps one day, DNA tests will be a vital
part in confirmation of Transsexualism along with the psychiatric evaluations The problem I could see from this would be the denial of treatment if the DNA proved otherwise.

32. Other studies also support the hypothesis that there are psychoneuroendocrinological
links in the development of transsexualism, that is, that the endocrine environment
impacts on the neural organisation of potentially sex dimorphic areas of the brain;
these, in turn, influence the psychological identification as male or female (Gooren,
1990; Swaab and Hofman, 1995; Zhou et al., 1995; Diamond, 2002; Kruijver et al.,
2000; 2002; 2003). Sex differentiation of the mammalian brain has been shown to be
initiated during fetal development and continues after birth (Phoenix et al, 1959;
Kawata, 1995; Chung et al., 2002). It is also postulated that the hormonal effects on
the brain occur at several critical periods of sex differentiation during which gender
identity may be established. So, at present, although the exact mechanism is
incompletely understood, it is hypothesised that an atypical hormone environment at a
critical time in the organisation of the fetal brain may be associated with an
inconsistent gender outcome (Kruijver, 2004).
33. It is postulated that, in those who experience severe gender dysphoria, the sex
differentiation of their brains has not followed the pattern usually predicted by the
earlier steps in the differentiation process (such as the chromosomes, genitalia and
gonads) “but has followed a pattern typical of the opposite sex in the final stage of
that differentiation process” (Gooren, 1999; Gooren and Kruijver, 2002). This
hypothesis is substantially supported by two important studies on post-mortem brains,
including those of trans individuals (Zhou et al., 1995; Kruijver et al., 2000).
34. These studies followed others that found several sex-dimorphic nuclei in the
hypothalamic and other areas of the brain (Allen & Gorski, 1990; Le Vay, 1993;
Swaab et al., 2001). Of particular interest, in regard to transsexualism, is the sexdimorphic
region called the central subdivision of the bed nucleus of the stria
terminalis (BSTc). This nucleus appears to become fully volumetrically sex
differentiated in the human brain by early adulthood. In human males the volume of
this nucleus is almost twice as large as in females and its number of neurons is almost
double (P <.006) (Zhou et al.,1995; Kruijver et al., 2000; Chung et al., 2002). The
Kruijver et al. study found that in the case of trans women (n=7), the size of this
nucleus and its neuron count was in the same range as that of the female controls
(n=13) and, therefore, women in the general population. When all the subjects were
included, the neuronal differences between the groups were found to be highly
significant. In the only available brain of a trans man, the volume and structure of this
nucleus was found to be in the range of the male controls (n=21) and, therefore, men
in the general population. The latter is not a significant result, but in the context of the
overall findings, it leads to the hypothesis that this male-like BSTc will be present in
other trans men as well.