> It only relatively recently came to be applied to sexual roles and identity.
OED has it being used equivalent to “sex” (in the sense of male v. female categories) back to 1474, which is not all that recent. It’s only recently that models splitting “sex” (physical traits), “ascribed gender” or just “gender” (socially recognized role), and “gender identity” (self-identified social role) as distinct things with distinct names have come into use, but “gender” wasn’t plucked out of linguistics alone for its use in regard to such models, but from its longstanding use as another label for “sex” as a categorization axis. (That it was also used in linguistics, which might be viewed as social, may be why it got picked for the social aspects and “sex” for the physical, I suppose.)
OED has it being used equivalent to “sex” (in the sense of male v. female categories) back to 1474, which is not all that recent. It’s only recently that models splitting “sex” (physical traits), “ascribed gender” or just “gender” (socially recognized role), and “gender identity” (self-identified social role) as distinct things with distinct names have come into use, but “gender” wasn’t plucked out of linguistics alone for its use in regard to such models, but from its longstanding use as another label for “sex” as a categorization axis. (That it was also used in linguistics, which might be viewed as social, may be why it got picked for the social aspects and “sex” for the physical, I suppose.)
[0] https://www.oed.com/viewdictionaryentry/Entry/77468