the intersex article is interesting too:

http://en.wikipedia.org/wiki/Intersex

definition of intersex: conditions in which chromosomal sex is inconsistent with phenotypic sex, or in which the phenotype is not classifiable as either male or female. Applying this ... precise definition, the true prevalence of intersex is seen to be about 0.018%.[1] ”

So there are about 50,000 intersex people (by Sax's definition) in the United States alone.

and apparently there is an official language choice:

Research in the late twentieth century has led to growing medical consensus that the diverse intersex physicalities are normal, but relatively rare, forms of human biology. Perhaps the most prominent researcher, Milton Diamond, stresses the importance of care in selection of language related to intersexuality.

“ Foremost, we advocate use of the terms "typical," "usual," or "most frequent" where it is more common to use the term "normal." When possible avoid expressions like maldeveloped or undeveloped, errors of development, defective genitals, abnormal, or mistakes of nature. Emphasize that all of these conditions are biologically understandable while they are statistically uncommon.[2]

and interestingly enough:

Since the rise of modern medical science in Western societies, some intersex people with ambiguous external genitalia have had their genitalia surgically modified to resemble either male or female genitals. But there are increasing calls for recognition of the various degrees of intersex as healthy variations which should not be subject to correction. Some have attacked the common Western practice of performing corrective surgery on the genitals of intersex people as a Western cultural equivalent of female genital cutting. Despite the attacks on the practice, most of the medical profession still supports it. Others have claimed that the talk about third sexes represents an ideological agenda to deride gender as a social construct whereas they believe gender is a biological reality.