Epigenetics is the study of changes in genes that are caused by a person's environment rather than alterations to their DNA.
Scientists in the field of epigenetics are interested in the way our behavior and experiences can influence our gene expression — essentially, which of our genes get turned on or off. They look at factors like early loving relationships, environmental toxins, and healthy food, and study how they change the way people's genes function. Epigenetics adds the Greek prefix epi-, "over or on top of," to genetics, "the study of heredity."