On the face of it men and women couldn’t be more different. I’m not talking about ‘Men are from Mars and Women are from Venus’. I mean just look at us, from body shapes to dangly bits – we are opposites.
However did you know the natural human form is female? Centuries of eunuchs show if a male never undergoes puberty, when the secondary sex characteristics kick in (i.e. shaving, sweating and football), the adult body is feminised. Without testosterone the male lays down layers of fatty tissue around the hips, breasts and bottom; body hair does not develop in male places and neither does male pattern baldness.
At conception if you get a pair of X-chromosomes you are female. Males have an X-chromosome from the mother and a Y-chromosome from the father. Despite this, every foetus starts off the same. It is only when the Sexual differentiation Region on the Y-chromosome (SRY gene) starts the production of testosterone the sexes diverge.
To put it simply the proto-ovaries become testes and migrate down; forcing the labia to expand becoming the scrotum, and what becomes the clitoris forms the penis. As a kid I remember being fascinated by the line on my scrotum that made it look as if it had been stitched together. Doing biology years later, all was revealed. It had been… stitched in the womb by the Hand of God!
Of course nothing is ever quite so simple as ‘male and female he created them’. Every aspect of our mind and body is subject to endless variety. Why should sex be different?
The truth is it isn’t. People are not just biologically male (XY) or female (XX). There is a whole range of human sexes resulting from genetic or developmental triggers.
In the womb, a foetus can be exposed to hormone levels unsuitable to the genetic sex resulting in inappropriate feminisation or masculinisation. This often only become evident during puberty when the secondary sex characteristics develop.
Both sexes make small amounts of the opposite sex’s hormones from puberty onwards. If dormant hormone receptors develop due to inappropriate hormone levels in the womb, men can develop breasts and other feminine characteristics while having male genitals. These are the original hermaphrodites from the ancient world.
Often female athletes have to undergo the public humiliation of sex testing. Some show the presence of testosterone receptors. More puzzling some women showed mosaicism, meaning some body cells have the usual double XX genotype, while other cells have XXY or XO.
Perhaps the most fascinating genetic anomaly is XXY. For if women are double XX and men are XY to what sex should a person with this genotype be assigned?
The condition is called Kleinfelter Syndrome. Children are male but with additional X-chromosomes (giving XXY or XXXY). Testosterone production suffers affecting fertility, the appearance of genitals, a lower muscle mass, reduced body and facial hair and breast tissue development. In later life they may experience diseases more normally associated with women such as breast cancer and osteoporosis.
In Turners Syndrome there is only 1 X-chromosome (XO) instead of 2. Sometimes there may be multiple X-chromosomes – XXX; XXXX. Children are female with some physical differences such as short stature, skin webbing around the neck and fingers and are often infertile.
In the past psychologists claimed XO women exhibited hyper-feminism, but as with XYY men (multiple Y-chromosomes) these studies probably reflected nothing more than the psychologists’ expectations.
XYY men (and other Y-chromosome multiples) occur when the original ball of cells begins to divide after conception. Studies classed such men as hyper-masculine: over-sexed, aggressive, lower IQ and poor concentration. However many of these studies took place within prisons.
In males with double sex chromosomes (XXYY) it appears the extra female X-chromosome overrides the additional male Y-chromosome producing low testosterone and all that entails. However some men with double sex chromosomes are not affected, so there may be other factors. We are only now beginning to understand how genes affect each other.
A remarkable story from a TV documentary haunted my imagination for decades. It told of a family of hermaphrodites who possessed male and female genitals, one testicle and one ovary, and chose their preferred sex at puberty. I was never able to find out more. I believe this is because the science had moved on, and these people were better understood.
What I heard about was Guevedoces. A name roughly translating as ‘eggs at 12’ – huevos or guevos being not only the Spanish word for egg but also slag for testicle.
Guevedoces are biological males, living in Dominican Republic, Turkey and Papua New Guinea, with a Y-chromosome mutation that prevents the foetus recognising the testosterone surge in the womb. They are born looking female, but their highly divergent genitals can resemble a male’s, a female’s or be indeterminate.
Youngsters are brought up as girls until the second testosterone surge at puberty. Then, like boys, they develop muscle mass, body hair, and miraculously their female genitalia transforms into a man’s, which works perfectly well, in most cases.
In the news there have been reports of very young children seeking gender reassignment. Often our first reaction is… how can they possibly know?
According to doctors working with the Guevedoces, the children do identify with their biological sex from an early age. Of course being human beings this is not always the case. Despite undergoing physical transformation some feel comfortable remaining female.
Which raises the age-old question… Is sexual identity nature or nurture?
The idea of being born with your sexual identity is confirmed by a distressing case.
In 1966 a mother gave birth to identical twin boys. A slip during the infant twins’ circumcision destroyed David’s penis. After consultation with psychologist John Money it was deemed best to transform David into a girl. This led to a unique situation, a boy and a girl with exactly the same genes would determine if we were born into our sexual identity or grew into it through being treated differently by society.
Money published a number of papers saying David’s transformation was a success. Nurture determined sexual identity.
However David claimed he never felt like a girl and as an adult claimed back his birth sex.
Further, John Money’s, no doubt well-intentioned, but shocking techniques, were called into question.
In 2002 David’s twin (aged 36) took an overdose of antidepressants.
In 2004 David (aged 38) shot himself in the head with a sawn-off shotgun.
Unsurprisingly the parents laid the blame for their sons’ tragic deaths firmly with John Money.