To prevent modern diseases such as obesity, cancer, cardiovascular conditions and diabetes, which have reached epidemic-like proportions in the last decades, many health experts have called for students to receive Health Education (HED) at school. Although this type of education aims mainly to improve children's health profiles, it might affect other family members as well. This paper exploits state HED reforms as quasi-natural experiments to estimate the causal impact of HED received by children on their parents' physical activity. We use data from the Panel Study of Income Dynamics (PSID) for the period 1999-2005 merged with data on state HED reforms from the National Association of State Boards of Education (NASBE) Health Policy Database, and the 2000 and 2006 School Health Policies and Programs Study (SHPPS). To identify the spillover effects of HED requirements on parents' behavior we use a "differences-in-differencesin-differences" (DDD) methodology in which we allow for different types of treatments. We find a positive effect of HED reforms at elementary school on parents' probability of doing light physical activity. The implementation of HED for the first time increases fathers' probability of engaging in physical activity in 14 percentage points, although it does not seem to affect mothers' probability of being physically active. We find evidence of two channels that may drive these spillovers. We conclude that information sharing between children and parents as well as the specialization of parents in doing typically-male or female activities with their children may play a role in generating these indirect effects and in turn in shaping healthy lifestyles within the household.JEL Classification: I12, I18, I28, C21.