Epigenetic features as biomarkers of past, present, and future exposures and health

Inherited from our parents, the human genome supplies the hardware of the body: a stable set of molecular components shared by all cells. Yet just as identical computers can perform different tasks depending on the software they run, cells with the same DNA can adopt vastly different identities. The incredible diversity in cell types across the body arises from the epigenome—the biological “software” that determines which gene programmes are active in each cell type. These instructions are encoded by molecular marks on top of our DNA and, intriguingly, continuously update in response to a vast number of factors, including both internal and external exposures, nutrition, age, and social conditions, allowing our cells to adapt over a lifetime. Epigenetic marks can record the past, shape the present, and predict—or influence—health far into the future by impacting biological processes such as gene expression, cell differentiation, and disease risk—sometimes across generations. Due to its central role in linking environment and biology, epigenetics—the study of these molecular changes—has a promising future in preventative and precision medicine. Therefore, understanding the epigenome, its regulatory mechanisms, and the interpretation of epigenetic biomarkers is key to decoding how our experiences influence lifelong health.