Plot: What will it mean when most of us can afford to have the information in our DNA—all three billion chemical letters of it—read, stored, and available for analysis? In "Cracking Your Genetic Code," NOVA reveals that we stand on the verge of a revolution. We meet cancer patients returned to robust health and a cystic fibrosis sufferer breathing easily because scientists have been able to pinpoint and neutralize the genetic abnormalities underlying their conditions