There are some people who have unusual genotypes like XXY. Further, it's possible for the transcription of a birth record to be just plain wrong. As such, there should be some sort of procedure for adjusting a person's birth record to reflect reality. Of course, someone seeking to alter their officially-recorded sex to match reality should be required to provide evidence that the change would actually have that effect.
I was talking about the devil-children like Cher's offspring . . . a butchered up, hormoned up, bearded "thing" (I can't think of a better word) that the media keeps referring to as he/him rather than she/her.