> The sex/gender distinction is an invention of the past 20 years
As a generalized concept (though descriptions of social systems with gender roles distinct from the commonly referenced sex binary are older still, though many of those written by members of societies which did not recognize such a distinctions, including Western European colonialists, were hampered by the absence of terminology to describe it simply) its significantly older than 20 years; with research projects and prominent works on gender identity, in the modern sense, being written as early as the 1950s and 1960s. While the bulk of the writing that early (and for some time after) on the subject pathologized identities that diverged from the social sex/gender correspondence stereotypes, it recognized that they existed, were largely a product of aspects of biology, and while they tended to held out that there was a social contribution to them which made them potentially malleable early on (and advised conversion therapy for that purpose), recognized that they were difficult to impossible to modify beyond early childhood, and in many cases recognized the value of gender confirming procedures beyond that point.