The DNA Test Delusion

Answers to our greatest questions, we were told about a decade ago, could be ours if we just spat in a tube. Celebrities were using DNA tests to trace their ancestry on the hit TV show Finding Your Roots. A “Who’s Your Daddy” truck rumbled through the streets of New York City, offering paternity tests on the go. Angelina Jolie sent droves of women scrambling to get their DNA tested when she wrote a 2013 op-ed in the New York Times. Jolie, whose mother was diagnosed with breast and ovarian cancer and died at 56, credited a DNA screening with identifying a mutation in her BRCA1 gene that meant she had an elevated risk for cancer, too. In detailing her choice to get a double mastectomy, she helped cement the popular understanding that a single gene could mean the difference between life and death.

A few months after the op-ed ran, during an appearance on CBS This Morning, 23andMe Chief Executive Officer Anne Wojcicki said she was bringing the power of these sorts of DNA tests to everyone. Her startup would make testing...