"Well, the first civilization I found myself inside -- that wasn't my native one -- thought that it was the man's responsibility to make intelligent conversation, and the woman's responsibility to look interested and giggle. Every man. Every woman. Also they were giant bug aliens with weird suboptimal equilibria where nobody had an individual incentive to express the thought 'what if we did something else which is not that' even though it was true, but that's a long story."
"In general, there are personality tropes and interpersonal relationship tropes; people sometimes fall into regular-ish categories of being people, and people with regular-ish traits sometimes interact with one another in regular-ish ways. 'Gendertropes' are a proper subset of personality tropes that are being primarily expressed relative to the proper subset of interpersonal relationships that are sexual or romantic relationships."
"To put it another way, if it makes sense to say that somebody is a 'man' or a 'woman' and not just that they have personalities, or that they're 'married' and not just hanging out with one another, it makes sense to subtype and subdivide them further for extra predictive points."