Radio Lab recently had a show called (So-Called) Life in which a woman in need of a transplant test her children’s DNA. They find that the children match the father’s DNA, but not hers! Additional testing reveals that the DNA in her blood is completely different from the DNA in her saliva — she is, essentially, two different people.<SPOILER ALERT>Basically, doctors have concluded that she is a chimera. That is, her mother was pregnant with two embryos that fused within the first few days of life. They did not blend, but rather the new embryo contained some of the parts from baby A and some of the parts from baby B — she was her own twin sister. To put it into perspective, if the eggs had not completely fused, this woman would have been Siamese Twins. Instead, she is both twins in one body.She started talking about the thought the she is two people, that her salivary glands differ from her circulatory system, that she has two different bodies inside of her. Naturally, this raised some interesting questions. What is her identity? Is she two people? Is she one person? What is a person, if the DNA suggests that she is two persons?