The Chimera is primarily known as a creature of Greek legend – a fire-breathing monster with parts of a goat and a lion with a serpent for a tail. In biology the term has come to refer to any organism that contains more than one set of genes. There are chimera African violets, where the core of the plant is genetically distinct from the outer layers. Animal chimeras, or mosaics, as they can also be called, don’t usually divide so neatly.
The most common form of human chimera is called a blood chimera. This happens when fraternal twins share some portion of the same placenta. Blood and blood-forming tissue is exchanged, and takes up residence in the bone marrow. Each twin is genetically separate except for their blood, which has two distinct sets of genes, and even two distinct blood types. Up to 8% of fraternal twins are blood chimeras, and as the incidence of fraternal twins in the general populace increases with the popularity of in vitro fertilization, the number of blood chimeras should rise proportionately. §
All I knew about Chimeras till date was that it was the codename of the drug or something in Mission Impossible: II. :) Interesting stuff.
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