Perhaps one of the only things we remember from eighth-grade biology is that DNA doesn’t change. The 3 billion letters that make up your personal genome are with you for life, a master blueprint handed down from your parents. But not everything about how your genes operate is programmed at birth. Simon Gregory, an associate professor of medical genetics and codirector of the Duke Epigenetics and Epigenomics Program, explains:
While the sequence of DNA may not be affected by your environment, the way genes work—called gene expression—can. Think of DNA as a computer’s hardware; there may be several types of softwareprograms that can regulate what the hardware does. Epigenetics is the study of heritable changes in gene expression that don’t involve changing the underlying DNA—effectively, software changes that cause alterations in gene function.
Environmental factors such as food, drugs, or exposure to toxins can cause epigenetic changes by altering the way molecules bind to DNA or changing the structure of proteins that DNA wraps around. These structural changes can result in slight changes in gene activity; they also can produce more dramatic changes by switching genes on when they should be off or vice versa.
These changes are heritable, meaning they can be passed on from parent cell to daughter cell within the body, and from parent to child. An extraordinary study of survivors of the Dutch famine during World War II, for example, has shown that the effect of epigenetic changes caused by hunger don’t show up in the survivors’ children, but they do in their children’s children. This perhaps suggests the adage should not merely be, “You are what you eat,” but also, “You are what your grandparents ate.”
To learn more about Duke’s research on epigenetics, visit www.genome.duke.edu/DEEP/.