This original documentary was broadcast in 2005 on the BBC. PBS NOVA has aired an updated version on October 16, 2007.
Scientists have long puzzled over the different fates of identical twins: both have the same genes, yet only one may develop a serious disease like cancer or autism. What's going on? Does some biological force beyond genes determine who we are? On October 16, 2007, NOVA's "Ghost In Your Genes" traces the clues that have led scientists to a new picture of genetic control and expression called epigenetics. This is genetic imprinting, how stress and other environmental factors in your ancestors can affect how genes are switched on or off in your body.