@FrightenedRat indeed gender isn't physiology and it isn't sexuality, but that doesn't mean you can perform a conceptual subtraction of those components and conclude that gender must be whatever else is left.
what is gender? my best answer to that is, it's a set of experiences - sensory, bodily, social, emotional, etc - that we have grouped together and put in this category. gender identity is said to be the sense of one's own gender, but for those of us who don't have a clear, strong sense of gender, or who are still exploring it, i think of it as a brief summary of one's gender experiences.
this makes gender, by its nature, multidimensional, nebulous, unstructured, without any particular core or primary component, and personalized to every individual. someone could share which gender experiences were most formative to them, and you could have conflicting experiences, or no equivalent experiences, or find them trivial.
therefore, i found learning about gender to be largely a process of listening to a great number of other people's experiences, and collecting the ones that felt relevant and meaningful to me. eventually i built up a sense of what constituted my gender and how it was different from other people's.
in that sense it was very similar to learning about neurodivergence; the constructs we have are similarly confusing, arbitrary, and possibly wrong, and we often figure out both the ideas and ourselves by relating (or not) to other people's experiences.
@GTMLosAngeles @Susan60 @marytzu @juliasnz @RolloTreadway