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The Probable Origins of G,L,B and T

(for Phillip and everyone else who wonders about these things)

By Dave


Over the years we’ve heard many theories about what causes variations in sexual orientation and gender self-identification, involving everything from Sigmund Freud’s weak fathers and overbearing mothers (long since debunked) to the elusive “gay gene.” In addition, there is the religious argument that being gay, lesbian, bisexual or transgender is a choice. (After all, it wouldn’t do to have it occur naturally since that would throw many closely held religious beliefs into question!)


We don’t yet know with 100% certainty what causes someone to be born G,L,B, or T. However, scientists are much closer to a workable and supportable theory than ever before. We do know for sure that it’s inborn – not a choice or an illness. That’s been proven with dozens of studies and statistical models, and was accepted by the American Psychological Association and the American Medical Association in the early 1970s, after decades of research and discussion.


What’s becoming clearer is the mechanism appears to involve a mix of genetics, epigenetics, and hormones. The precise details aren’t clear yet, partly due to our inability to test human fetuses at various stages of development. We may be stuck with just a good theory for a long time to come unless a specific genetic variant or trigger is found.


My Theory, Explained

First, let me say that I'm not a scientist, just a lay observer. While I studied psychology many years ago, I'm not in the field now and gain my knowledge watching from the sidelines. I may have a few details wrong.


Every fetus is initially female. At about seven weeks into the pregnancy, the baby’s genetics trigger a hormone “wash” that bathes its developing brain in a mix of the female hormone estrogen and the male hormone testosterone. This wash apparently initiates a change in the brain’s development, guiding it towards female or male.  The percentage of estrogen vs. testosterone apparently varies widely, following the statistical rules of standard distribution - true randomness as depicted by a bell curve. That is, most people receive a “typical” mix. The further off-center the mix is, the fewer fetuses receive it.


This is where we get to the similarities and differences between G,L,B and T. We'll use a male example here, although the same concept would be true for females. The initially female fetus’ brain with male genetics triggers the hormone wash. If it’s in the typical average balance, you get a pretty average heterosexual guy. However, if the mix is off, say with too much testosterone and not enough estrogen, you end up with a hyper-masculine brain. If there is too little testosterone and too much estrogen, you get a more feminine male brain.


The further the mix is from the average, the greater the difference in the brain. For instance, if you get a bit too much estrogen, you might just get a "sensitive" guy – still heterosexual, but with some female traits. If the mix were even further off, he might identify as bi-sexual. A bit further off, and he would identify as gay. At the extreme, the hormone mix would be the same as for a typical genetic female, resulting in a transgender person – one with the body of one sex, but the brain of the opposite gender. (Sex is what you see – the physical body. Gender is how you identify yourself, male or female.) The opposite also occurs - an increasingly all-testosterone wash - the far end of the scale would be a hyper-masculine guy.


Statistically, we know that heterosexuals are the largest group, followed by bisexuals, then homosexuals, and finally transgender. This fact supports the hormone wash theory quite well, since the variability in both self-identification and hormone mix would follow the standard distribution, and plot nicely as a bell curve.


Can we prove this theory beyond any doubt? Not yet. We have no way to measure a human fetus’ hormones in vitro, and we can’t watch the genetic or epigenetic triggers in action. We can only infer from animal experiments and retrospective studies. However, for all practical purposes the theory seems to fit reality so well that I feel comfortable publishing it.


The Younger Brother Theory

There is another possible cause under discussion that involves only certain gay men. Researchers have learned that a significant number of gay men were the youngest of several males in a family. It didn’t matter if they had several older sisters, but if they had several older brothers, the odds of being gay increased significantly. The theory, as yet provable only with statistics and what we know about the body’s reaction to imbalances, is that the mother’s body sees the male testosterone levels in the womb as a danger and tries to overcome it with additional estrogen, resulting in an off-balance, more feminine mix. This theory doesn’t work for lesbian women, of course, but that doesn’t change its viability as a theory for gay men. It could just be a less common or alternate trigger for the off-balance hormone wash that applies only to males.


A Continuum

One final lesson that can be learned from this theory: being G,L,B, or T isn’t always a clear-cut thing. Obviously, since the hormone mix is almost infinitely variable, you can fall anywhere along a scale from hyper-male or hyper-female to transgender. If someone falls somewhere in between clear identities it can be very confusing, hence self descriptions like "pan-sexual."


The Bell Curve

The Gray Scale

 Compare this with the bell curve plot above - they represent the same data with a different visual tool.



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