Due to the symptoms he would be exhibiting, a genital examination would be conducted. With the specific subtype I was attempting to pull from, the genitals become quite obviously abnormal after infancy, and that combined with a blood test for the hormone deficiency would narrow down exactly what subtype and what chromosomes the character had. After further research replying to a different comment, I have gotten some things cleared up on CAH subtypes I do realize this is not possible but not for the reasons you have brought up. (with the actual subtypes now as I understand it, he would either have to have a subtype that gives him standard female genitalia & late diagnosis, or ambiguous genitalia & early diagnosis, due to the life threatening complications only present in the second case.)

I set up that framework as a suggestion for how it might work in the setting, not as the setting itself. That was one way my brain provided to rationalize it, I admit a shabby one but that is why I came here; because I knew what I was writing was shabby.

To be quite honest I’m not sure why I wrote that specific line you quoted the way I did, I had not slept for 40 hours when I wrote it. If I rewrote it now I’d have been much clearer.