[CobaltBlue]

Something like one out of every 20,000 males are born with androgen insensitivity syndrome, which makes them genetically male but apparently female.
http://www.emedicine.com/PED/topic2222.htm

I once knew a married couple where I was fairly certain that the wife had androgen insensitivity syndrome and was genetically male, while the husband was sort of straight but not really. It worked for them.

[Paul C. Jesup]

Thanks for the link. It is a good article.