A Washington State University researcher has demonstrated that a variety of environmental toxicants have negative effects on not just an exposed animal but the next three generations of its offspring. The animal's DNA sequence remains unchanged, but the compounds change the way genes turn on and off -- the epigenetic effect studied by molecular biologist Michael Skinner. While Skinner's earlier research has shown similar effects from a pesticide and fungicide, this is the first to show a greater variety of toxicants -- including jet fuel, dioxin, plastics, and the pesticides DEET and permethrin. Skinner's work demonstrates that diseases can also stem from older, ancestral exposures that are then mediated through epigenetic changes in sperm. "In the future we might be able to use these epigenetic biomarkers to determine your ancestral and personnel exposure early in life, and to predict your susceptibility to get a disease later in life," Skinner says.