If somebody who is by all hitherto accepted standards a male tells us he is actually female, we are faced essentially with only two options: we either accept in our hearts and minds that he really is a female trapped in a male body or we assume he's deluded.
Likewise, if somebody who is by all hitherto accepted standards Bert Higginbottom, a 42-year-old bus driver from Huddersfield, tells us that he is actually Napoleon Bonaparte, we are faced essentially with the same two options: we either accept in our hearts and minds that he really is Napoleon trapped in Bert's body or we assume he's deluded.
Personally, I welcome the world's increasing acceptance that people are in fact what they believe themselves to be.
I could go on and say that if someone believes himself to be a giraffe we should treat him in every way as if he is a giraffe and you might reply "Oh, you're just getting sillier and sillier now!"
But am I? Have a think about it.
Is there any real difference between any of the three situations above?
It gets even more complicated when a circle announces that it's a triangle but we are dealing with exactly the same thing as in all the other examples.
Perhaps it would help to reduce the whole problem to mathematics?
If A is not equal to B yet claims to be equal to B, we have two options: we either deny their equivalence or we alter our definitions of one or the other (or both) in order to allow their equivalence.
In every case given above, it's not a matter of what something "really" is or what something "really" isn't: it's a matter of how we choose to define that something.
Reality is a funny thing, folks - mainly because it doesn't exist!