Modern medical science has told us that there are probably some 20+ genders to deal with and the forms which litter our lives which ask if we are male or female are inadequate.
Science itself tells us never to simply accept what we see with our own eyes, natural systems are far more complex. I don’t think anyone can argue strongly against self defining what one feels oneself to be and/or what medical examination tells us.
The issues of how we design wider society in the acceptance of this is, of course, more difficult. But that there are more than 2 genders is now an established fact.