The I Ching's Perspective on Gender

It's important to note that at its core, the I Ching system is a Binary system; it's yin/yang, 1 and 2.  These express themselves as simple binaries (at the level of individual lines being yang-male or yin-female) and complex binaries (ie. the combination of two trigrams, where you might have for example the combination of a trigram that's two-parts yin one-part yang with a trigram that's three parts yang; or that sort of thing).

So with regard to gender, the perspective that the symbolic/mathematical language of I Ching takes is of necessity that there isn't a spectrum of entirely different types of gender (eg. gender-1, gender-2, gender-3, gender-5, gender-52) which are all inherently different from one another; but that there's a spectrum of genders that are different accumulations of those two basic forces (eg. at the level of trigrams this would be something like male-3, male-2 female-1, male-1 female-2, female-3; at the level of hexagrams things like male-4 female-2, male-3 female-3, etc.).

There is an added degree of complexity when you understand that it's not just the quantity of yin and yang in each trigram/hexagram that matters, but also where the lines are placed. So female-2 male-1 where the one male line is at the bottom is a different expression than female-2 male-1 where the one male line is in the center.

I think that at times, there is a tendency to imagine that the I Ching is fairly absolutist about gender, after all Yang is "male" and Yin is "female".  But remember that there, we are talking about "constituent forces".  Yin and Yang as separate forces exist Nowhere at the material level of reality; the I Ching is really saying that while at dimensions beyond the actual manifested material world we live in, you can talk about something Archetypical or even Primordially "male" or "female".  But at the level of manifestation (the hexagrams), in our actual world, there's nothing that is only purely male or only purely female.  Even the hexagrams #1 and #2, which consist of all "male" lines and all "female" lines respectively, and are thus as-male/female-as-you-can-get in this level of reality, still have within them the potential for changing.  Any one of the lines that is solid can theoretically become a changing line and then mutate into its opposite.  So even those two cases cannot be thought of as "Absolute" in their maleness or femaleness.