Book excerpt: Bill Griffeth, longtime genealogy buff, takes a DNA test that has an unexpected outcome: "If the results were correct, it meant that the family tree I had spent years documenting was not my own." Bill undertakes a quest to solve the mystery of his origins, which shakes his sense of identity. As he takes us on his journey, we learn about choices made by his ancestors, parents, and others - and we see Bill measure and weigh his own difficult choices as he confronts the past.