Changeling

A changeling, in European fairy folklore going back centuries, is a fairy or other supernatural being's own child that has been secretly swapped for a stolen human infant — the substitute often described as sickly, strange-eyed, or unnervingly "off" in ways the family senses but cannot quite name. Folklorists and UFO researcher Jacques Vallée, in his influential comparative work on fairy lore and abduction accounts, identified the changeling motif as the pre-modern ancestor of the modern hybrid-nursery abduction narrative: the same underlying structural fear — an outside, non-human intelligence taking a human infant or reproductive material for its own purposes — recurs across centuries and cultures wearing whatever costume the era supplies, fairies in the 1600s and grey aliens in the 1980s. Vallée's larger argument, developed in his book "Passport to Magonia," is that treating UFO occupant and abduction reports as a wholly new phenomenon starting in 1947 or 1961 ignores a much longer continuous folklore tradition of non-human beings interacting with, and sometimes abducting, humans. Skeptics of the parallel argue that structural similarity between any two supernatural-encounter traditions is nearly inevitable given how few basic story shapes human folklore tends to reuse, and doesn't by itself prove either changelings or hybrids describe a real external phenomenon.