When I'm teaching AP-level Biology, we do cover cell communication and signal transduction pathways. Our case study is commonly an impala encountering a cheetah, and the resulting epinephrine dump and how cells process a response. I know I already commented in this thread but I've been reading this article piecemeal and this struck me:

In an episode where Jazz visits a surgeon and has a discussion about sexual function, Jazz states: “I haven’t experienced any sexual sensation.” Regarding orgasm, Jazz says: “I don’t know, I haven’t experienced it.” The male genitalia are awaiting testosterone to change from a pre-pubescent state to an adult state in which sexual function is possible. In the normal adult state, there is full sexual function. In one episode, Jazz’s pediatric endocrinologist states that Jazz has adult female levels of estrogen. This, however, has not given Jazz “any sexual sensation.” This makes sense physiologically, as the male genitalia (penis, scrotum, testicles, etc.) are awaiting testosterone to develop, not estrogen.

When I teach my students the most basic thing about cell communication, one thing they learn is that without a receptor, there cannot be a response. This allows your whole body to be awash in a hormone or some other molecular cue, but only certain cells will respond. On top of that, different cells will have different pathways that lead to different responses.

So you dump a female cocktail of hormones on some dude, because he already has breast tissue, there will be some response to hormones. But if the target tissue isn't there, say the uterus, the receptors aren't there either, so what do these people think they're accomplishing? The hormones don't build structures. HRS for people unhappy with the sex they were born with is such obvious horseshit pseudoscience, so of course people are buying into it. Everyone wants a simple magical pill and no one wants to really understand how complex the body really is.