You swab your cheek or spit into a vial, then send it away to a lab somewhere. Weeks later you get a report that might tell you where your ancestors came from or if you carry certain genetic risks. Or the report could reveal a long-buried family secret and upend your entire sense of identity. Soon a lark becomes an obsession, an incessant desire to find answers to questions at the core of your being, like "Who am I?" and "Where did I come from?" Welcome to the age of home genetic testing.

In The Lost Family, journalist Libby Copeland investigates what happens when we embark on a vast social experiment with little understanding of the ramifications. Copeland explores the culture of genealogy buffs, the science of DNA, and the business of companies like Ancestry and 23andMe, all while tracing the story of one woman, her unusual results, and a relentless methodical drive for answers that becomes a thoroughly modern genetic detective story.

The Lost Family delves into the many lives that have been irrevocably changed by home DNA tests--a technology that represents the end of family secrets. There are the adoptees who've used the tests to find their birth parents; donor-conceived adults who suddenly discover they have more than fifty siblings; hundreds of thousands of Americans who discover their fathers aren't biologically related to them, a phenomenon so common it is known as a "non-paternity event"; and individuals who are left to grapple with their conceptions of race and ethnicity when their true ancestral histories are discovered. Throughout these accounts, Copeland explores the impulse toward genetic essentialism and raises the question of how much our genes should get to tell us about who we are. With more than thirty million people having undergone home DNA testing, the answer to that question is more important than ever.

Gripping and masterfully told, The Lost Family is a spectacular book on a big, timely subject.