That's pretty easy, RH. I think that YJ said, people should use their own morality to decide whether to disclose.
I think the whole question here is whether we 'should' consider a MtF to be woman...
The XX/XY comments made in this thread make it clear that some people think chromosomes define sex and gender, whereas i'm pretty sure society would base gender more on behaviour, and sex on body... never minding that this remains a simplification of the non-binary nature of our chromosomes.
Not everyone is born with either male/female genitalia, they are usually assigned at birth - ostensibly to make them 'fit in' - is that so society doesn't have to accept there is more than just the binary simplification, or is it to make the child's life less stressful??
Does the reality of variation in humans not belie the homo/hetero stereotype - you can be attracted to many people and there will be variation within that set, some of them may have XY chromosomes (but also androgen insensitivity syndrome) - you are attracted to what you are attracted to, and choose to have sex with whomever you choose to have sex with? What difference does birth assignment have to do with it?
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Oh, and for females, born XY but not sensitive to testosterone (ie androgen insensitivity syndrome) so she developed both physically and mentally as female - though without ovaries, internal testicals instead... thus at puberty she will not begin to menstruate or become fertile... Should they tell potential partners before they first have sex??