Are there any stats available on the dates of Dsd within gids ?
As I said earlier, the reported rate is zero cases in about 5000 patients.
That's because people with DSD don't have gender dysphoria but serious medical issues which may or may not come with being assigned a sex (the one and only correct usage of the term) and any resulting issues from this assignment turning out wrong.
However, this is extremely rare. Statistically speaking, every two years one person with a DSD in the UK decides to have their sex reassigned because the doctors got it wrong at birth. But the doctors don't simply guess and assign a sex arbitrarily where a baby isn't obviously male or female at birth.
1 in 5000 babies require specialist input in determining sex - these are cases of a baby born with ambiguous genitalia.
That's approximately 130 babies per year in the UK. In about 7 or 8 of these babies, even specialist input does not lead to conclusive results and sex is assigned based on all available results and discussion with the parents.
Taking the numbers over a two year span, this sex assignment may eventually be found to be wrong for 1 of these babies. That's 1 in 260 babies with ambiguous genitalia, or 0.0001% of the population.
(Those numbers are from the submission to the Scottish Census Draft Bill by dsdfamilies, a small charity supporting parents of children diagnosed with a DSD as well as the children themselves.)
So, no sex is not a spectrum and even 94 to 95% of children born with ambiguous genitalia can after investigation be determined to be unequivocally male or female. There are no true hermaphrodites in humans (that is persons capable of producing both types of gametes, neither at the same time nor one after the other), and there are no non-binary bodies.
For a little linguistics exploration:
non-binary ordinarily denotes something not consisting of, composed of, indicating or involving just two (systems, or classes or characteristics etc).
Mathematically speaking it denotes not having a base of 2. Like the decimal or hexadecimal number systems.
But even a baby who at birth undergoes intensive evaluation for a DSD and whose sex must still be assigned on an educated best outcome basis, does not have and will not develop a body that is non-binary.
Because there are only two sexes in humans, so even a person with characteristics of both sexes will not ever be non-binary as there are two and only two sexes whose different characteristics may be present. There may be typical male and female characteristics to varying degrees, but there are no characteristics of a third sex present.
And if that zoology professor uses the word in the sense of neither male nor female, again this isn't strictly speaking true. But more importantly this kind of othering of people with DSDs, of putting them into a third category is considered incredibly offensive by them.