So we have cis followers, so we should say this. The soy = estrogen thing is not sciencey, it's a bigoted talking point.
As far as we're aware, the hate rhetoric came first, but there are actually scammers out there who, trying to prey on trans-feminine people, sell soy products which they claim are a form of cheap, unregulated HRT.
They're lying. Those products do not work.
They're lying. Those products do not work.
If there were any way to make the human body even a tiny bit more feminine through the use of soy products, the trans community would have found it. (Many trans people are actual chemists!)
If we had to guess at the origin of the rhetoric, we think the simplest hypothesis is: Soy is often seen as a foodstuff that only leftists like, and rhetorically, people who promote hate find it advantageous to spread the idea that all their political opponents are the same.
Because having a single "enemy" is easier to sell. Because it reduces repetition. You only have to teach the idea of hating others once, and then you expand the definition of that group.
Also there are indeed estrogen-related chemicals in soy (which are not usable for HRT, not even with post-processing), so the lie has a kernel of truth, as many of the best lies do.
The context for this thread is that a Republican Congressional candidate tweeted a bigoted callback to it. This is one of those things that comes up a lot though, so, now we have a thread on it to refer people to.
This is one of the many medical details which are not at all obscure to trans people, most of us learn this stuff from each other at some point. It *is* obscure to people who've never had a reason to learn it, and it's frustrating seeing people not know something "obvious".