Iain M. Banks said this quote

Marain, the Culture’s quintessentially wonderful language (so the Culture will tell you), has, as any schoolkid knows, one personal pronoun to cover females, males, in-betweens, neuters, children, drones, Minds, other sentient machines, and every life-form capable of scraping together anything remotely resembling a nervous system and the rudiments of language (or a good excuse for not having either). Naturally, there are ways of specifying a person’s sex in Marain, but they’re not used in everyday conversation