Nonhuman studies would almost certainly be more definitive as gender identity (in humans) is hugely compounded with exogenous societal, cultural, political, and medical factors. As an example of the latter, until recently considered a diagnosible and treatable medical and/or psychological disorder.

Disentangling those factors would be exceedingly difficult, although longitudinal cross-cultural studies (possibly widely separated twins) might get you somewhere.

Animal model populations' medical institutional bias is somewhat lower.

The simplest explanation is that it's 'acceptable' to be trans in 2019. Plastic didn't make people gay, but the gay population increased in the mid to late 1900s just as the trans population is increasing now.

There aren't just the social factors with coming out, but also the education around being being trans. Some people live their entire lives not knowing and only find out after watching youtube, meeting people in the community, or going to therapy (which is also becoming more commonplace and acceptable). The stigma attached to trans people as mentally unwell 'others' prevented people from even considering it for most of their lives.

Also, I do not believe there is an unbalance of trans woman to trans men. Trans women are more controversial (bathrooms) than trans men, which puts them in a public spotlight. Trans women often present themselves as stereotypical women, and if they've not fully medically/surgically transitioned yet, it makes them easy to pick out in a crowd. Trans men, on the other hand, wear men's clothes, which happen to be gender neutral if worn casually. They are often seen as 'butch' women if not fully transitioned, not trans men. You oftentimes probably wouldn't notice or identify trans men when you see them.

Disclaimer: I'm a trans woman.

This is a taboo rather than a dumb question.

So much of our identity is special to us. How would you feel as a gay man if someone told you that the reason your sexuality was not standard heterosexual was because your mum's womb was knackered from having seven kids and you were last in the line?

This is a thing, but, after spending a teenage coming out, it is just a bit of a harsh thing to be told.

Since we can't even discuss this yet, what chance is there that we will have the conversation about how pollution is messing up our fertility and gender?

Largest reason is that trans, homosexual and bisexual people don't have to fear being killed or shunned by their families or in school any more. (Yes, in reality they do have to fear discrimination, but soxiety as a large has gotten way, way more open in the last 30 years!)

Trans people were known in ancient Greece ffs, it's mostly thanks to the Catholic church and its "morals" that we ended up with imprisoning people for being gay or trans.

Do you have citations for that being the reason? And what about societies outside of Catholic influence? Seems odd to blame them.

And I never said they didn’t exist, so I’m not sure why you seem to have an aggressive tone. I know they’ve always existed. But with research showing intersex births becoming more common than ever, I have to wonder if there’s a connection to rates of being trans as well.

The Catholic Church policy on condoms was blamed for the high rates of HIV in Africa and yet if you looked at the stats, the countries where protestantism was more predominant than Catholicism had higher rates and vice versa. Not claiming there was any causation there but the original allegation had no basis. If someone is going to flout church teaching on sex outside marriage they are hardly going to be worried about flouting it by using a condom.

I'm curious why you feel its the Catholic church specifically. My understanding is that strong disapproval of gay or trans people is common throughout the Abrahamic religions.

It is, but he or she said "mostly" because of the catholic church and that might be true, because they are the oldest and still most powerful single organization of the abrahamic religions.

Ehm, oldest only if you count Christianity as a special Judaic sect.

What's an older and more powerful single institution of an abrahamic religion? I can only guess you are referring to something involving Judaism but there is nothing even remotely like the Catholic church (large, rich, organized, formal creed, central authority, standardized practice across large territories) in thousands of years of the history of Judaism.

Is there an older Abrahamic organization? He did say organization.

There isn't really any research either way that I'm aware of. Without knowing the likely cause of gender dysphoria, we can't really know if the factors I listed would be relevant.

That said, I think it's worth investigating. Here's a paper from Scott Kerlin, showing the results of survey from DES sons. It's a group of people born as male to women given DES, an estrogen affecting drug.

http://worldaa1.miniserver.com/~gires/assets/Research-Assets...

"More than 150 network members with “confirmed” or “strongly suspected” prenatal DES exposure status indicated they are either transsexual (pre- or post-operative, 90 members), transgender (48 members), “gender dysphoric” (17 members), or intersex (3 members)."

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A strong caveat to this would be that people don't just join a group called DES sons on a whim. A large number of women were given DES. Many more than 500 sons were born to them. People who joined the group are self selecting as having had some sort of problem or concern to discuss.

And that's almost all I could find on the topic. The only other thing that seemed notable is that the brains of transgender people resemble those of their chosen sex, not their birth sex. I.e. a MTF person had a brain typical of a women, not a man. But, this difference may only appear in adulthood, so it isn't clear if it is physiological or social.

If someone wanted to investigate this, investigating the testicular and endocrinal health of MTF people before transition would be a good start. If endocrine disruption had anything to do with it you would expect to see much more testicular cancer. The DES group had 5 out of 500 with this cancer, incidentally, while having a low cancer incidence overall.

I would categorize the published research on this topic as extremely slim. It's not even at the hypothesis stage, and your question isn't answerable without much further research.

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Oh also, while traditionally there were more MTF, recently gender dysphoria clinics are reporting more FTM.

Here are some numbers from the UK: http://gids.nhs.uk/number-referrals

The year on year referral increase is very large. So social acceptance/awareness must have a sizeable role. Endocrine dysruption can't explain a ~4x increase in 5 years.

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Edit: I should have included this: https://en.m.wikipedia.org/wiki/Causes_of_transsexuality

Doesn't touch on endocrine disruption in terms of estrogen exposure though.

> It's a group of people born as male to women given DES

I haven't researched it further, but I heard a theory that female hormonal contraception is a contributor to people identifying as LGBT.