The tests are nonetheless popular. Ancestry, for instance, reported sales of 1.7 million kits during the 2017 Black Friday weekend, and the company says it has six million people in its DNA ...

Another company also markets its test as the most accurate dog DNA test. The most expensive test, purchased for $288, is from Embark, a Boston-based company and research partner of Cornell University.

Ever since DNA was first used in 1986 to catch a killer, it's swashbuckled its way through society as an almost infallible weapon of truth: convicting the guilty, freeing the innocent, revealing ...