The nouns of sex and gender are often conflated, but can be better understood as distinct qualities: sex refers to physiological concerns whereas gender refers to social role, perception and identity.
Sex, as in physiological or “biological” sex, is not quite as clear-cut or binary as most people think; roughly 1 in 1,000 babies are born “intersex” with dual-sex aspects that can span genitalia, hormones or chromosomes; also, most of those physical characteristics can be altered by surgery or hormones (and some day, genetic editing).
Gender , as in gender role or perception of gender, has substantial variation, since there is a high degree of human individuation in a world of 7+ billion humans and also because gender norms vary widely by culture and historical time period (for example, in USA, pink used to be a “very masculine” color and powder blue was considered “feminine,” but these colors later “swapped” gender affiliation). Also, it’s worth noting that some historical cultures have had more than 2 genders, such as “two-spirits” in indigenous American cultures, and “hijras” in India.
Most people seem to fall heedlessly into one of the mainstream binary gender categories (“man” or “woman”) – they are cisgender. Those of us who defy perception or cultural expectations for our “assigned gender” [based on sex at birth] are transgender or genderqueer (these categories span a large gamut, including transsexuals [at all levels of transformation], various types of gender non-conforming people like non-binary, androgyne, agender or gender-fluid individuals, as well as feminine gay men, butch lesbians, and those who may play with gender on a less frequent basis, as occasional drag kings or queens or cross-dressers).
For the record, I identify as androgyne or gender non-binary.
Even among the cisgendered, very few fit perfectly into one category (most have at least a few traits that don’t fit into their assigned gender category) and thus they’re heavily policed, both externally and internally. Frequent cultural messaging espouses what “real” men or women should be like and demands expression of [cisgender appropriate] masculinity or femininity. It’s widely accepted as an insult to suggest that a person’s gender is like the “opposite” gender. Doesn’t all that policing and gender outrage get tiresome?
I suggest we drop all those gendered expectations and insecurity down the memory hole. Let people express themselves how they are and define their own identities, within the bounds of mutual respect.
If you want more in-depth discussion of my perspectives on gender, check the links:
See also my GenDissent thesis
(from 2000, my college days)