The Baxley family turns out to carry a high risk of genetic disease. Gina Kolata, medical reporter for The New York Times and the author of Mercies in Disguise: A Story of Hope, a Family's Genetic Destiny, and the Science That Rescued Them  (St. Martin's Press, 2017), tells their story as DNA testing offers the opportunity for individual members to find out for sure, and the possibility of preventing passing it on, at a steep price.