We’ve all heard of the saying, "You are what you eat," but what about "You are what your great-grandparents ate?" That’s just what a new study from Washington State University is suggesting. The researchers found that ancestral exposure to the pesticide methoxychlor could lead to health complications many generations face down the line.

In an experiment to see how far the effects of environmental pollution reached, scientists at Washington State University exposed rats to methoxychlor. This pesticide was first introduced in 1948 and was widely used in the 1970s, since it was, at the time, regarded as a “safer alternative” to DDT. The methoxychlor, also known was Chemform, Methoxo, Metox, or Moxie, was sprayed on crops, ornamental plants, livestock, and pets, according to the press release.

After exposing the gestating rats to a level of methoxychlor equivalent to that of high environmental exposure, Michael Skinner and his team saw some rather disturbing results. There was an increase in the occurrence of kidney disease, ovary disease, and obesity that seemed to remain for up to three generations. "What your great-grandmother was exposed to during pregnancy, like the pesticide methoxychlor, may promote a dramatic increase in your susceptibility to develop disease, and you will pass this on to your grandchildren in the absence of any continued exposures," Skinner explained in the press release.

Although methoxychlor was banned in the United States in 2003, its ability to span generations is alarming. The researchers believe that the pesticide was able to affect how genes are turned on or off in the different generation of exposed animals, even without changing the actual DNA sequence of the organism, in something called transgenerational epigenetic inheritance.

Skinner suggests the past exposure to methoxychlor may be one of the reasons for America’s increasing rates of obesity and disease in the past 50 years. Exposure to this pesticide has been linked to reduced fertility, increased adult onset of disease, and of course, the possibility of passing these traits on to future offspring.This is the first study to show that most transgenerational disease traits are passed on via the mother. However, the researchers did identify mutations in certain genes in the sperm of great-grandchild male rats.

According to the Environmental Protection Agency, methoxychlor was used as an insecticide due to its effectiveness against pests such as house flies, biting flies, cockroaches, and mosquito larvae. It can pass on to humans by inhalation, handling, or ingestion.

Source: Skinner MK, Mannikkam M, Haque MM, et al. Pesticide Methoxychlor Promotes the Epigentic Transgenerational Inheritance of Adult-Onset Disease through the Female Germline. PLOS ONE. 2014