OK, some of you may not like my reasoning, and that's OK with me, but here goes:
Quoting from the KJV as my ultimate authority:
"So God created man in his own image, in the image of God created he him; male and female created he them."
I would posit that aberrations from these two categories, physical or mental, natural or surgical, are therefore subcategories of same. Granted there can be and is varying presence or absence of physical characteristics of both. When you get into attempting to have a major category for every possible variation is where you really get into the weeds. Are you going to uniquely categorize everything from one testicle, two testicles, one breast, two breasts, regular vs. inverted nipples? Then what do you do if an individual, due to multiple characteristics fits into more than one of the above? How about circumcised, uncircumcised, castrated, sterilized... Your option is pretty much limited to a new category. Creating arbitrary categories can only lead to the creation of MORE arbitrary categories. And the more there are, the less useful they become.
One of the best days of my IT career was they day I told my boss if the problem was so simple he should go fix it himself.