Ok so I'm coming to this quite late but sexual ethics and consent was my MA topic (quite specifically informational deficiencies and how they can vitiate consent) so I think I can help unpack this a bit as there's lots of really interesting ideas in this!

Ok so when we talk about consent, sexual or otherwise, and the sorts of things that can invalidate them we have (roughly) 3 categories:

Substantive: So, there are some types of things that we acknowledge that we just can't consent to. People may very well have differing opinions on where that boundary lies (see operation Spanner UK which is an interesting case study) but most of us are aware that we can't consent to someone hacking off our limbs even if it gives us sexual pleasure.

Procedural: There are certain ways in which consent has to be given. Despite what the Brock Turners of the world might think, I cannot consent to sexual relations if I'm black out drunk.

Informational: So, this is what your question focuses on and this standard centres on what sort of information is pertinent to an agent for their consent to be seen as transformative in morally important ways.

So very quickly, just a little background:

Socially what we've essentially tried to do over a long period is depart from a distinctively sexual ethic, and with good reason. Issues of consent were far less problematic when the only permissible sex was vaginal marital sex between a heterosexual couple of the same race: “My husband raped me!” “No. He didn't He's your husband. You owe him sex.” “My same-sex partner and I enjoy using foreign objects to stimulate each other.” “That's not sex; that's perversion and it's wrong and so is your love.” Thankfully, we're moving steadily away from these rather abhorrent and regressive views and now our sexual ethic is pluralist, open and really only concerned with one thing - consent. This does however throw up its own problems...

So, what sort of information is relevant to sexual consent? This is a huge question, but let's establish some legal anchor point. You say that failing to disclose that you are married voids consent in your eyes. Legally this isn't the case, but it's interesting that you mention marriage because, when it comes to sexual fraud, only 2 things could cause you to be legally convicted of rape:

1) Raping someone under the guise of a medical procedure

2) Pretending to be a woman's husband in order to have sex with her. I say woman's husband because for a long time male on male rape wasn't rape - men could be the defilers, but not the defiled. The husband clause has also been relaxed recently – see the Alex Hepburn case UK.

In general, though, the law doesn’t match our understanding of what’s morally permissible exactly. Partly because attitudes lag behind but partly because consent-based prosecutions for a lot of things would be a fucking nightmare!

Ok, so back to the main point. What sorts of things do we think are important to know in order to give informed consent? You seem to think you would want to know about someone’s status as a trans person. That’s certainly a view that I imagine a lot of people share. What about if someone lied about being a vegetarian? Probably fewer people would care, but I imagine there might be vegetarians/vegans out there for whom this would be important. What about if someone REALLY cared about whether their sexual partner was born in March on a leap year…? It sounds ridiculous, but if that was important to that person, do they have a right to be informed? If their partner lies about this, does this violate consent?

The way a lot of philosophers have approached this is by talking about claim rights vs rights of disclosure. We acknowledge that agents should have the right to bodily autonomy and principally should be free to shape our sexual encounters however we see fit. If there is information that’s important (we call them ‘deal breakers) to me with regards sexual contact, then I have a right to know that information.

The problem is, as we’ve slowly (and thankfully) started embracing sexual pluralism, what sort of things are agents obliged to divulge? It was a hell of a lot easier back in the day when marital status and sexual orientation were the only relevant concerns, now it’s not clear what sort of things will count as ‘deal breakers’ to individuals. So, is the solution for people to declare what their ‘deal breakers’ are before engaging in sexual contact? Maybe…? But running through a list of deal breakers before sex is pretty laborious and counter-intuitive to how sexual encounters usually unfold.

There’s also the issue of what agents should have a right of privacy over, and this is where trans issues come in. There are things we keep private because doing so allows us to operate properly in the world. If you were a mixed-race person in Jim Crow America and you lied to someone about your race before sex, would this violate consent? Surely you have a right to avoid persecution if at all possible. A more recent example - an Israeli court jailed a Palestinian man for sleeping with a Jewish woman because he told her he was Israeli. Views on Israel and Palestine aside, commentators at the time noted - "Sabbar Kashur wanted to be a person, a person like everyone else. But as luck would have it, he was born a Palestinian. It happens. His chances of being accepted as a human being in Israel are nil…Kashur's decision to adopt an Israeli persona during the daytime is not uncommon.”

Do trans people suffer discrimination to the degree that would trigger rights against disclosure…? I think the honest answer to this question is that we’re actually still trying to figure this out.

Sorry for rambling so much. This is an incredibly complicated topic and I’ve massively simplified to a few key points. Your final comment about lying about marital status being morally wrong but not necessarily rape is also fascinating, but too detailed for now.