If the Greys aren't real, where did the idea of them come from?

Paul Bennewitz by 1981 had known about the 'Big-headed Grey' alien. Bill Moore said that the term Grey was given to Paul through the computer network he had created, because anywhere in the time of the 60s of the Hill story or the 70s of Travis Walton's story, you will not hear anyone saying the term 'grey'. The actual term grey was probably an inside name given to this species because there was another species that was orange, so they just named them as nicknames by the colors and it stuck, which also could have been disinformation. One small fact is that both of the individuals aware of aliens this early - Bennewitz and Budd Hopkins, both said that aliens are not grey but are blank white with no hair. This is around 1981 and I don't think anyone can bring up a cite on the term 'grey' before then.