A
genetic chimerism or
chimera (also spelled
chimaera) (not to be confused with the cartilaginous fish called
Chimaera) (from the creature
Chimera in
Greek mythology) is a single organism composed of cells from different
zygotes. This can result in male and female organs, two blood types, or subtle variations in form. Animal chimeras are produced by the merger of multiple fertilized eggs. In plant chimeras, however, the distinct types of tissue may originate from the same
zygote, and the difference is often due to
mutation during ordinary
cell division. Normally, chimærism is not visible on casual inspection; however, it has been detected in the course of proving parentage.