Obesity is a risk factor for numerous diseases, including cancer and type 2 diabetes. This risk extends to future generations, as parental obesity can leave epigenetic marks in egg and sperm cells that affect the metabolic health of offspring formed from those germ cells. “The health status of the parents matters,” says Zhen Yan, a physician scientist at the University of Virginia. In a new study, Yan and his colleagues investigated whether exercise started during pregnancy is enough to improve offspring health in mice.