thats rare .i wonder what the stats on that are ..i mean in the face of a population of 9 billion does it really warrant such a change
Not sure just how common chromosomal aberrations are (I suspect very rare).
Usually people have XX or XY gender chromosomes. An XX is a female, an XY is a male. The gender chromosomes that determine one's gender come from the father - the mother will always pass on an X chromosome while the father may pass on an X or a Y.
I remember many years ago when I was studying human biology it was known that there were a few non-standard combinations that occasionally appeared. From what I recall (and it was 25-odd years ago, so don't ask for sources!) XXY was considered to be the most common "non-standard" combination while XXXY and XYY were also known.
It's always hard to know when to add a new option to something where the proportion of people expected to use the new option is very small but depending on the application it may be that something more than "male" or "female" is required. For the sake of example, if you're dealing with someone who is physically male but identifies as female it's one thing to discuss which bathroom they should use but another thing entirely to discuss who they should share a university room with. A man might be uncomfortable sharing living space with someone who identifies as female, while a woman might be uncomfortable sharing living space with someone who is physically male.