The term "Chimera," in medical parlance, refers to a person whose body possesses two distinct DNA signatures. Named for a term from Greek mythology that referred to an animal that was a mixture of a lion, snake, and goat, this newly described phenomenon occurs when two zygotes are conceived as fraternal twins but early in their development merge to become a single fetus. Associated with the hermaphroditism (or inter-sexed) phenomenon this condition has only recently been recognized in medical literature as a result of DNA research.
When this occurs different organs and body parts will show differing DNA signatures. For example, a Chimera's skin, blood, and hair might show one signature while the internal organs might have a different DNA signature. How and why this condition occurs is not clearly understood nor is it known for sure how frequently this occurs.