The risks of sharing your DNA with online companies aren’t a future concern. They’re here now

Turmoil at 23andMe, a company offering popular at-home DNA testing, has upset the industry. Following the resignation of every independent member of the company’s board of directors, its chief executive, Anne Wojcicki, expressed openness to selling the company and its database of around 15 million customers, raising concerns about the misuse of genetic data.

Although Wojcicki has since said she is focused on taking 23andMe private, the data-sharing risks raised by DNA testing and matching companies are already here. A class-action lawsuit filed in August alleges that the operator of GEDmatch.com, a genealogy site that claims to have a database of more than 1 million members, has been sharing users’ information with Facebook. This revelation should alarm us all.

GEDmatch stands apart from companies such as 23andMe. It’s an open, crowdsourced database that anyone can search. Founded in 2010, it emerged as a tool for genealogy enthusiasts to upload DNA results and connect with relatives. It gained notoriety when law enforcement officials announced in 2018 that they had used the service to identify the Golden State...