According to the Intersex Society of North America, there are varying definitions of intersexuality. People who don't fit neatly into the binary system of "male" and "female" gender assignment could include those with atypical chromosomes, those with atypical genital anatomy, and others with "subtler forms of sex anatomy variations." Depending on who you include, estimates of how common intersexuality is vary, but the Society gives a general estimate of "total number of people whose bodies differ from standard male or female" as 1 in 100 births.
It's not all that unusual to be intersexed. It's certainly not unnatural. (I know that it happens in other species besides humans, too. The frog I dissected in high school appeared to be anatomically male from the outside, yet turned out to have fully developed ovaries. My first intersex encounter.) Yet, for some reason, intersexuality is rarely portrayed in fiction.
Have I ever read a book of fiction with an intersex character before? I thought maybe I had, in Up For Grabs: Exploring the Worlds of Gender, an anthology from Circlet Press. When I look over the reviews, though, it looks like the five stories are about transgender, not intersexed, characters. I like transgendered fiction, too, but this blog post is not about that.
According to this post, a few works of fiction that feature intersex, or non-binary-gendered, characters include Middlesex by Jeffrey Eugenides, Robin Hobb's Farseer and Tawny Man trilogies, Chiyo Rokuhana's I.S.: Otoko demo Onna demo nai Sei manga (in Japanese) and Ursula K. LeGuin's The Left Hand of Darkness.
If you're looking for nonfiction about intersexuality, there are a few choices, including Bodies in Doubt: An American History of Intersex by Elizabeth Reis, Fixing Sex by Katrina Karkazis and the memoir Intersex (for Lack of a Better Word) by Thea Hillman.
I have not read any of these books, but I did read a good intersex fan fiction short story last night. Its author is Tumblr user Kmmerc, who - does not have an "About" page, so I know very little. By now you are well familiar with my pop-cultural obsession with the U.S. television show Person of Interest, so it will not shock you when I say Kmmerc is a fellow Irrelevant and the fanfic is set in the POI universe (although, clearly, an alternative universe).
The story title is "A Cock and Ball Story" (your clue that the story will be about anatomical structures) and the parts (of the story!) are:
So I really like this. Normally when you take a fictional world of some kind and genderbend it, you make the male characters female and/or the female characters male, but this is an approach to "genderbent" fiction I've never encountered before.
More, please. More genderbent fan fiction, and more original intersexed characters. The fluid and non-binary aspects of human gender are so fascinating to explore - let's go there. Let's go there in erotica and in general literary fiction as well.