Babies switched at birth

Babies are occasionally switched at birth or soon thereafter, leading to the babies being unknowingly raised by parents who are not their biological parents. The occurrence has historically rarely been discovered in real life, but since the availability of genealogical testing of DNA has been discovered more frequently, and likely went undiscovered more often in the past. The phenomenon has been common as a plot device in fiction since the 18th century. The exchange may be accidental, or (particularly in fiction) purposeful. The babies may be referred to as changelings.