Quote from: Anna-Maria on October 06, 2014, 01:41:19 PM
...what influences the development of sex and gender is still unknown and one has to remind that in such a complex issue monocausalistic justifications will never make the point.
Not so! Sexual development in birds and mammals is entirely hormone-driven, something that was first demonstrated in experiments with guinea pigs in 1959, and since been shown to be the case in a wide range of mammal and bird species. There's also a medical condition in humans called Complete Androgen Insensitivity Syndrome (CAIS), which basically proves that male development only takes place in the presence of androgenic hormones (primarily testosterone and its derivative DHT), and without the action of these hormones, you'll develop as female instead, irrespective of what your genes might say.
The people in those videos are genetically male, they have a fully functioning Y chromosome, internal testicles in place of ovaries, and normal to above normal male levels of testosterone too! Nonetheless, they've developed both physically and psychologically as female. The only difference between these people and the genetically male people who become men is a mutation to a single gene, which has rendered the androgen receptors throughout their bodies inoperative. As a result, all their prenatal development took place as if there were no testosterone present.
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There are myriads of possible sources of influences on the baby, interruptions, dysfunctions caused by meiosis in the sperm production, the hormonal level in the womb, external factors (environment etc.) or genetical specialties and the research is just at a starting point and not holistic as far as I know.
For example, you can fully develop as "male" with no obvious sign of intersex/transsexual condition, while carrying an XX karyotype (so-called de-la-Chapelle-Syndrome, see link to Wikipedia http://en.wikipedia.org/wiki/XX_male_syndrome ) and reverse (the prevalence of XY-women is so high that the International Olympic Committee abolished standardized chromosomal analyses for women´s competitions at the Olympic Games).
In De La Chappelle syndrome, the SRY gene (which normally lives on the Y chromosome), has translocated onto an X chromosome. This is the gene that causes the embryonic gonads to turn into testicles (without it they'll turn into ovaries instead). In addition to SRY, the Y chromosome contains a few dozen other genes, which are primarily concerned with spermatogenesis. Since XX males don't have these genes, their testicles are unable to produce viable sperm and so they're infertile. They still produce testosterone though, which is why people with De La Chappelle develop as male and usually have a male gender identity.
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De-la-Chapelle syndrome is often only discovered if the man in question gets his chromosomes analyzed because of infertility, so we just can guess about the prevalence in the overall population.
The most interesting part indeed is that, most of these males still have a male subconscious sex (or gender identity if you will) even if they are almost 100 % female in their chromosomal setting, while the prelavence of Transsexualism in these men is not significantly higher than in the majority at least as far as we know it. And research done to this point is very little.
In order to get a better insight to this interesting yet scientifically underrepresented phenomenon, here in Germany before starting HRT a chromosomal analysis is made up standard now. I´m curious about my results 
xx
Anna-Maria
Historically, I think most cases of intersex and transgender had a genetic basis, however hormones are now so widely used in medicine (especially womens medicine) that I think most of us alive today are likely to be the unintended result of the medical use of hormones during pregnancy. It's difficult to see how someone such as myself could be the result of any conventional cause of intersex - genital development fully male, with some parts of my brain development quite strongly male while other parts appear to have been completely female. Most conventional causes of intersex tend to act throughout the pregnancy, they don't cause some parts of a person's prenatal development to be fully male and other parts to be fully female.
