Monday, August 23, 2010

Identical Twins Do Not Have Identical DNA

My husband just sent me an article about a 2008 study that has reported monozygotic ("identical") twins do not have identical DNA.
Until recently, any differences between twins had largely been attributed to environmental influences (otherwise known as "nurture"), but a recent study contradicts that belief.
Geneticist Carl Bruder of the University of Alabama at Birmingham, and his colleagues closely compared the genomes of 19 sets of adult identical twins. In some cases, one twin's DNA differed from the other's at various points on their genomes.
For example, one twin in Bruder's study was missing some genes on particular chromosomes that indicated a risk of leukemia, which he indeed suffered. The other twin did not.
"Maybe we shouldn't call them identical twins," Harvard's Bieber says. "We should call them 'one-egg twins.'"
The implications of this study are interesting to the study of orientation, perhaps explaining why monozygotic twins are far more likely to have identical orientations than the general population, but do not always have matching orientations.

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