More than thirty million people have used at-home DNA testing kits, sold by companies such as 23andMe, Ancestry and others, to flesh out their family tree or to help them discover long-lost relatives. However, mail-in genetic tests can sometimes bring unexpected and unsettling results that challenge long-held assumptions about who we think we are.

In her book, “The Lost Family,” journalist Libby Copeland investigates the consequences of the commercialization of our genes and considers the implications for our privacy, our health and our relationships with family members and even law enforcement.