How are Aborigine children able to score so well on memory tests? Why do Europeans have a higher alcohol tolerance than Asians? What makes Kenyans such extraordinary marathon runners? Drawing from a fascinating array of examples, this program uses outstanding graphics and illuminating metaphors to bring home the power of a set of chemical instructions called genes. Laboratory experiments and real-life cases also show the dramatic effects of mutations, such as atavism and albinism. As scientists discover what these genetic switches control, the grim fact of heredity—that two out of three people will die for reasons connected with the genes they carry—may be relegated to the dustbin of history. A BBC Production. (59 minutes)