A Washington State University researcher Michael Skinner has demonstrated that a variety of environmental toxicants– including jet fuel, dioxin, plastics and the pesticides DEET and permethrin — can 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.
http://www.sciencedaily.com/releases/2012/03/120302101821.htm