Do Androids Dream of Electric Sheep? was published in 1968. Grim and foreboding, even today it is a masterpiece ahead of its time.
By 2021, the World War had killed millions, driving entire species into extinction and sending mankind off-planet. Those who remained coveted any living creature, and for people who couldn't afford one, companies built incredibly realistic simulacrae: horses, birds, cats, sheep...
They even built humans.
Emigrees to Mars received androids so sophisticated it was impossible to tell them from true men or women. Fearful of the havoc these artificial humans could wreak, the government banned them from Earth. But when androids didn't want to be identified, they just blended in.