Recounting the story of a girl who discovered through genomic testing that her brother was actually her uncle, Daniel Engber considers how genetic testing companies deal with potentially startling results:
23andMe does take some steps to warn its users of the risks. The top question on the company FAQ is “What unexpected things might I learn?” and the answer mentions that “genetic information can also reveal that someone you thought you were related to is not your biological kin. This happens most frequently in the case of paternity.” The terms of service specify that “once you obtain your Genetic Information, the knowledge is irrevocable,” and that “you may learn information about yourself that you do not anticipate” and “may provoke strong emotion.”
Yet it’s also true that the chances of discovering a case of nonpaternity through 23andMe, and the relative significance of that discovery, far outweigh almost every other finding that the service can provide. Much of what the scan can tell you is perfectly trivial. Do you have the genes for blue eyes or red hair? (For a first approximation, try looking in the mirror.) Do you have the genes for tasting bitterness in Brussels sprouts? (Maybe, but who cares?) After Steven Pinker signed up for 23andMe, he wrote in the New York Times Magazine, “For all the narcissistic pleasure that comes from poring over clues to my inner makeup, I soon realized that I was using my knowledge of myself to make sense of the genetic readout, not the other way around.”
The Dish 