Nearly half of the adult U.S population, 117 million people, lives with one or more chronic disease today, according to the Center for Disease Control. Seventy-five percent of the total U.S health care budget, amounting to almost $1.5 trillion dollars per year is spent on chronic diseases such as diabetes, heart disease, stroke, cancer, obesity, and asthma . On a global scale, chronic diseases are now the leading cause of morbidity and mortality and are becoming a serious burden for both developed and developing countries. While the global prevalence and related costs have become impossible to ignore, often times what is forgotten is that well over half of these diseases are preventable through modifications to lifestyle and health behaviors such as diet, exercise, or other environmental exposures . Epigenetics, a fairly new scientific field, targets the particular chemical pathways through which these modifiable factors such as diet and lifestyle choices can alter gene expression, determining the onset and development of chronic diseases. The chemical molecules involved in these pathways that alter gene expression independent from changes in the DNA sequence can be naturally produced by our bodies, consumed through our diet, or we can be exposed to them through the environment. This article will outline the emergence of the epigenetic field and the epigenetic mechanisms discovered to be associated with changes in gene expression. The majority of the article will then discuss current research that focuses on how environmental influences throughout an organism’s life can modulate the susceptibility and prevention of chronic diseases through epigenetic events.