There's no such thing as gender separate from sex. There's the recognition of one's immutable, inherent, sex, and tacking social expectations on top of it, but never that one could choose, or "feel". Always derived, never a choice. And when people allowed cross-dressing, it was always clear it was fake, pretending, never true. But they allowed people to have their personal delusions.

The origin of this use of "gender" itself is due to the prudishness of English upper classes in pronouncing the word "sex", so they repurposed "gender" which is just the French word "genre" meaning "kind" or "category". Much more acceptable in polite company than something that can allude to a sexual act, fornication.