I missed this last week:  Washington State University scientists have found that exposure to toxic substances can have effects that span generations.  From the Seattle Post-Intelligencer article:

The standard view of heritable disease is that for any disorder or disease to be inherited, a gene must go bad (mutate) and that gene must get passed on to the offspring.

What [WSU researcher Michael] Skinner and his colleagues did is show that exposing a pregnant rat to high doses of a class of pesticides known as "endocrine disruptors" causes an inherited reproductive disorder in male rats that is passed on without any genetic mutation…"It’s not a change in the DNA sequence," Skinner explained. "It’s a chemical modification of the DNA."

What, in particular, was the problem that was passed from generation to generation?  Apparently, the predilection for low sperm counts.

[Skinner’s] lab was studying testes development in fetal rats, using a fungicide used in vineyards (vinclozin) and a common pesticide (methoxychlor) to disrupt the process. A researcher inadvertently allowed two of the exposed rats to breed, so the scientists figured they’d just see what happened.

The male in the breeding pair was born with a low sperm count and other disorders because of the mother’s exposure to toxins. No surprise. But the male offspring of the pair also had these problems, as did the next two generations of male rats.

So what this all means is that, in theory at least, if your great-grandparent was exposed to an environmental toxic, it’s possible that you could be feeling the effects.  Ouch.