Quote from: LizMarie on March 26, 2015, 11:51:46 AM
Agreed, Hugh! And that's part of the problem. There is no neat single picture that captures this. It is a spectrum of effects. I think we have to remember that. I never had the stereotypical male V shaped upper body. Rather I had a very androgynous body and in high school I was even teased (playfully) that in a track warmup suit from behind I looked like one of the girls (longer hair, very straight body structure). My t-levels before beginning HRT we below normal. My "normal" was 290 when the normal range is 300-1200 with preferred "healthy" range being 400-600. (I think it's ng/dl units but don't recall for certain offhand.)
According to this study:
http://press.endocrine.org/doi/full/10.1210/jc.2010-3012the average (mean) total T for normal, healthy men is 723.8 ng/dl. There are a lot of doctors trying to tell their patients that levels far below that are "normal", however there's no scientific basis for those claims. From my own experiences and what I've seen people saying in the hypogonadism forums I subscribe to, once your total T drops below about 500 ng/dl, it becomes more and more likely that you'll start developing symptoms of hypogonadism (depression, loss of motivation, inability to think clearly, ED, muscle wasting etc).
It's only relatively recently that I've had my hormone levels measured, however there are signs that I've had below normal male T levels all my life.

This is a montage of photos of me when I was aged about 12, which I've been using to illustrate how my body structure is different from a normal male's. You can see that I've got feminine-looking facial features, long, slender arms and legs, my legs are very long in relation to my upper body, I've got a female digit ratio (ring and index fingers are almost exactly the same length). In the third photo I'm standing next to my older brother, and you can see how he's got a totally different build to me - a much heavier bone structure and much more heavily built overall, and although we're almost exactly the same height, his legs are noticeably shorter and his trunk noticeably longer than my own. My brothers (and even one of my sisters) developed severe acne as teenagers, whereas my skin remained almost totally clear (apparently, that's another symptom of reduced sex hormone production). In my case, the low T production is definitely due to secondary hypogonadism (meaning that my testicles are OK and the problem lies with the hormone-regulating regions of my brain, the hypothalamus and pituitary), since I'm currently treating it quite successfully with fertility drugs.
Other unusual things about me are that I was born with a genital abnormality called a hydrocele, which is something that's associated with lowered androgen levels during prenatal development. I've also got quite feminine body language, and, as a teenager, had the same problems of shyness and being bullied and ostracized that seem to very commonly happen as a result of DES exposure. My whole life story is quite similar to what seems to commonly happen to DES "sons", the main difference being that I don't fully identify as a woman, but rather, there's some parts of me that are quite strongly male, other parts that are quite strongly female, and probably some things that are neither male nor female too (although it's hard to tell, since I have no way of knowing for sure how other people experience the world!).
Based on what I've seen of the effects of DES, I was definitely exposed to synthetic female hormones during my prenatal development. I think the reason only part of my identity ended up female is that the exposure was during the second trimester only, and I had normal male development during both the first and third trimesters. With DES (and similar hormone treatments), the exposure was typically during the second and third trimesters, so you'd only get normal male development during the first trimester (and female development for the remainder of the pregnancy).
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So there's no single "thing" that marks us as trans, though there is a huge body of evidence that white matter brain structures play a role. Most of the thinking in that area assigns it to prenatal hormone ratios in utero, but as others note, there may be genetic factors that impact that as well, making it more or less obvious.
If you look at people with the condition Complete Androgen Insensitivity Syndrome, their resemblance to ordinary women (despite being genetically male) is so strong, that it shows that male development in people must essentially entirely be due to the action of androgenic hormones (testosterone and DHT) on androgen receptors, with genetic or other factors playing at best only a very minor role. The only difference between CAIS women and the genetic males who turn into men is a single mutation to the gene for the androgen receptors, that makes the cells throughout their body completely unable to detect or react to androgenic hormones. In all other respects they're exactly the same as the genetic males who turn into men, with a fully functioning Y chromosome, internal testicles in place of ovaries, and even normal to high T levels (although the mutation renders them completely insensitive to T, so it has no effect on them). In humans, maleness is entirely driven through the action of androgenic hormones on androgen receptors. This is something that's very counterintuitive, but nonetheless, it's not having a Y chromosome that makes you male, it's being exposed to androgenic hormones during your prenatal development. Being exposed to DES, or anything else that suppresses testosterone, during that critical time, can cause part of your prenatal development to occur as female instead of male, as I believe has happened to me and to millions of other genetically male people when our mothers were given DES or similar during their pregnancies with us.