Overrated “precision medicine” may just be serving vested interests, and consumer DNA testing can be useless—or even worse. Today, you can get your DNA sequenced—the letters of your entire genetic code spelled out—for about a thousand dollars, a bargain compared to the $100 million or so it cost 20 years ago. And for around a hundred dollars, you can get partial DNA sequencing. Direct-to-consumer genetic testing is “only a click away,” like 23andMe, for “ancestry, health, love…and more.” Unfortunately, many tests that are available today haven’t been validated properly. And, as a result, the b...