Person from the original comment, in the country where gender markers are only possible if you’re intersex. Some people are determined to be intersex at birth, but you can get diagnosed later. That’s usually when you phenotypically fit into the sex binary, but your hormone levels are above a certain threshold.

The threshold is kinda low, so e.g. me, AFAB, will get tested for T levels, and, if I’m lucky, be diagnosed as hormonally intersex, and be able to match the official gender marker to my gender (I can choose between X, something that’s currently eluding me and no marker, and will go for the latter). Kinda like how some cis women are excluded from women’s sports for having too much T, except in this case, it’s wanted. Low key considering using bodybuilder T to skew the test, since it’s bullshit that the gender marker can’t reflect my gender.

Edit: T is testosterone. There’s also many other types of intersex that also aren’t ‘having both parts’. Could be that there’s ovaries inside and masc-reading genitals outside, or that the genitalia doesn’t match the sex chromosomes, could be having more than two sex chromosomes (like XXY or XYY instead of just XX or XY), could be you go through a kinda puberty that doesn’t match a purely estrogen based or testosterone based puberty, e.g. growing both breasts and a beard. There’s sooo many possibilities, some of which will easily be caught at birth, some of which will only be caught later, or even never.