46,XX males are rare. Non SrY males are rarer, even the 46,XY ones. Not every Y chromosome has the SrY gene on, though most do. It can be translocated elsewhere, or missing entirely, and still masculinisation happens due to other causes.
47,XXY males on the other hand are around 1 in 450.
Considering all such situations (46,XX/46,XY mosaics, etc), 1 in 300 males are not 46,XY.
“ We then apply the average percentage of men that show no SRY whatsoever and we find that only 15/2,250,000 men has XX male syndrome AND shows no SRY.”
Don’t put too much faith in exact numbers, “around 1 in 150,000” is about as accurate as we can say at our present state of knowledge, and “around 1 in 20,000 to 25,000” for 46,XX men generally.
Parenthetically, 1 in 200,000 is the arbitrary threshold for a “rare disease”.
“ Let’s just agree that at this point, we can objectively determine a person’s biological sex through a number of factors.”
The problem is that there’s disagreement on what those factors are, and what the person’s sex is.
From Gloucester County School Board v. G.G — interACT: Advocates for Intersex Youth, et al. (Pdf)
“ Notably, the legal system has struggled for decades to answer the definitional question that Petitioner simply begs. By the time Title IX was enacted, courts well recognized that “(t)here are several criteria or standards which may be relevant in determining the sex of an individual.”
M.T. v. J.T., 355 A.2d 204, 206–08 (N.J. App. Div. 1976) (listing chromosomes, external genitalia, gonads, secondary sex characteristics, and hormones, as well as gender identity).
Commentators have noted the “variability of standards that courts employ” in making such determinations.
Even courts in the same jurisdiction have disagreed about how to determine sex when physiological features do not align.
Petitioner and its amici also assert that “physiological” sex has the virtue of being an “objective” classification. Pet. Br. at 32; McHugh Br. at 3–6, 12–13.
Gender identity, they suggest, is “fuzzy and mercurial,” id. at 8, while “physiological” sex simply is. But the foregoing discussion should make clear that this assertion is similarly flawed. An intersex student’s “physiological” sex may depend entirely on which Physiological trait one chooses to privilege. Indeed, because of the diversity of medical perspectives, trained experts can and do disagree on the “correct” sex to assign to an intersex child.
Interpreting “sex” to refer to a student’s gender identity would avoid (or at least mitigate) these problems. Unlike “physiological” sex, all parties appear to agree on what gender identity means: it is “[an] individual’s ‘innate sense of being male or female.’” Pet. Br. at 36; cf. Resp. Br. at 2 (similar). It is not subject to competing definitions depending on which expert or court is consulted. Moreover, unlike “physiological” sex, a student’s gender identity by definition cannot be subject to differences in medical opinion: each student is the ultimate arbiter of their own gender identity, as they (and they alone) experience it first-hand.”
