The internet has made DNA testing a big global business. In the United States and Europe, millions of people have sent samples of their saliva to commercial labs in the hopes of learning something new about their personal health or lineage. Ancestry.com, 23andMe, MyHeritage, and FamilyTreeDNA are all industry leaders that sell their services online, share test results on websites, and even provide guides on how to find relatives in phone directories or share results on social media. They frequently claim ownership of your genetic information and sell access to their databases to large...