Some interesting history of changelings:

Among the diseases or disabilities with symptoms that match the description of changelings in various legends are spina bifida, cystic fibrosis, PKU, progeria, Down syndrome, homocystinuria, Williams syndrome, Hurler syndrome, Hunter syndrome, autism spectrum disorder, Prader-Willi Syndrome, and cerebral palsy. The greater incidence of congenital disabilities in boys correlates to the belief that male infants were more likely to be taken by fairies. Psychologist Stuart Vyse writes that modern parents have higher expectations of childbirth, and when “children don’t meet these expectations, parents sometimes find a different demon to blame.” A condition known as regressive autism, where children appear to follow normal development in their early years and then start to show symptoms of autism, can also be compared to marks of a changeling child.

Some autistic adults have come to identify with changelings (or other replacements, such as aliens) due to their experiences of feeling out of place in the world.