Somewhere

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 something else besides genes determine who we are?
The "something else" turns out to be a network of chemical switches that sit on our DNA, turning genes off and on.
The program looks at the controversial cutting edge of this burgeoning new field. At the M. D. Anderson Cancer Center in Houston, Texas, researchers are investigating epigenetic means to treat a deadly form of leukemia. In Washington State, a researcher finds that a toxin given to rats still affects their offspring four generations later, without producing any changes in their genes. And in Sweden, a study of historical records seems to show that the lifespan of grandchildren is affected by their grandparents' access to food. Might these effects be epigenetic? Might our experiences, by changing our epigenomes, literally change the fate of our offspring ... and their offspring ... and theirs in turn?