DNA testing has become very popular among genealogists. The birth certificates, census records, and other documents they usually rely on can be wrong. DNA is never wrong. It can’t be altered, or forged, and you can’t misfile it. You can’t even always destroy it: DNA has been recovered from a frozen, 5,000-year-old corpse and used to identify his living descendants. Genetics do not uncover everyday family secrets such as the fact your great-great-grandfather owned slaves (unless he fathered children with some of them) or that a great uncle flunked out of West Point—it reveals the family secret, from whence you came, your begat. And your tree very likely has some invasive branches. As you look further up the tree, the chances of a non-paternal event rise exponentially. After 10 generations, you have 1,024 ancestors—I’m telling you, someone strayed. That’s why it’s prudent to trace families, not pedigrees.
You read these alarming stories once in a while about men who were first enthused about testing but then troubled when they discovered they aren’t who they thought they were, at least biologically, or that they have a half-brother they didn’t know about, or that an unsuspecting, elderly uncle doesn’t match any other male in the family (do you break it to him?). A hyperventilating, cautionary report posted last year at Vox.com trumpeted that genetic testing can unexpectedly tear families apart with revelations that are especially painful “when users aren’t looking for them in the first place.” As the databases at testing sites such as 23andMe grow, it warned, “there will be more and more family reunions, many of them by users who have no idea they are coming and aren’t prepared for them.” The article was accompanied by an essay by a reproductive biologist who had submitted his Y-DNA and that of his father for analysis. After the samples were processed, “George Doe” and his father both opted to see close matches. As George recounted, a user identified only as Thomas was shown to be a 50 percent match to George’s father—a son. George’s father professed to know nothing about Thomas, but George said the revelation unleashed “years of repressed memories and emotions,” presumably because Thomas had been conceived during an affair.
Read full original article: Your DNA Is Nothing Special