Biology stands on the brink of a shift in the understanding of inheritance. The discovery of epigenetics hidden influences upon the genes could affect every aspect of our lives.
At the heart of this new field is a simple but contentious idea that genes have a 'memory'. That the lives of your grandparents the air they breathed, the food they ate, even the things they saw can directly affect you, decades later, despite your never experiencing these things yourself. And that what you do in your lifetime could in turn affect your grandchildren.

part II: http://www.youtube.com/watch?v=iUyEmr1oTTE&feature=related
part III: http://www.youtube.com/watch?v=d9SB0teMQo0&feature=related
part IV: http://www.youtube.com/watch?v=Kc7LXkuebCI&feature=related
part V: http://www.youtube.com/watch?v=KkScrdldW68&feature=related