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?
JOHN JOSEPH DOLAN says
Geez, sounds like an episode of HOUSE
HEATHER BETTE HUGHES says
i think there are many factors to consider here. genetic code, gene expression, and environmental influences, to name a few. consider the following similarly statistically probable phenomenon in human development as the woman (chimera) mentioned above: two fraternal twins, one male, one female, can be entirely genetically dissimilar. that is, it is about equally as likely that two children born of the same parents have no dna in common as it is for the woman in the above story to have ‘two selves’. in fact, on the average, siblings from the same maternal and paternal gene pool are anywhere from only 25% to 75% genetically similar. so, what does this say for identity? in both cases mentioned here, identity is obviously informed by more than any one factor, genetic, social, or otherwise. for genetically dissimilar fraternal twins, especially those with no knowledge of their genetic dissimilarity, the socio-environmental influences of their upbringing (as kin) in a family/community (cultural context), if it occurs this way, would seem to counter-balance, if not override, any biological differences between them as their identities are formed in the context of their familial relationship.
bsr11 says
That’s an interesting line of thinking, Heather. If I understand you correctly, identity — like so many other elements the human experience — is part of the Nature vs. Nurture debate, and you suggest that the answer to identity lies in Nature AND Nurture? I asked the questions in my blog entry without taking the time to answer them myself, but I am pretty sure I like where you went with this.
Can you imagine your thoughts toward identity upon hearing that you are, genetically speaking, two different people? I recommend giving the episode a listen; the link is on my blog entry.