With genuine transgender, I have given the example of someone that (1) genuinely believes, (2) has that identity in the longer term, (3) has made a decision to embrace it and "transition".
So should people who are transracial or transabled also be considered 'genuine'? If Rachel Dolezal has her skin and hair permanently darkened should this be considered a genuine "transition"?
What about transabled people? If they can persuade a surgeon to amputate their limbs should this be considered a genuine "transition"?
As I understand it, you consider a "genuine" transgender, transracial or transabled person to be someone whose delusion is so strong that they "genuinely believe" it and that they have undergone some sort of physical modification to make them more physically like the person they think they should be.
If you believe this is true for "gender" but not for race or disability, can you explain what you believe the difference to be?
So while we can't strictly know if you want to be a hyper skeptic about it, in practice we would look at multiple people's reports, and then consider if their behaviour is consistent with it. We could also consider whether they have a reason to lie.
I can say with some certainty, looking at the reports of multiple prominent males who identify as transwomen that their behaviour is consistent with being misogynists and/or porn addicts and/or self-hating homosexuals.
They have all sorts of reasons to lie if their aim is to gain access to unconsenting women and/or children to play out their fantasies or if they are mediocre sportsmen who want to win for a change.
But what do you think they might be lying about? A man might genuinely believe that he wants to be his porn-soaked idea of what a woman is. That doesn't mean that I should recognise him as anything other than a man with a paraphilia.