The Bad News Forebears

Study suggests toxins' effects may be passed down through generations

A pregnant woman's exposure to toxic chemicals may cause harmful effects not only in her children, but in her grandchildren and theirs, a surprising new study suggests. For some time scientists have known about "epigenetic" changes: chemical modifications of DNA that affect the way it is expressed (phenotype), without changing the genetic code itself (genotype). What Washington State University researchers discovered -- and report this week in the journal Science -- is that such changes can be passed from generation to generation. This, suffice it to say, flies in the face of some fairly central assumptions in biology. It also raises disturbing questions about the long-term effects of chemical pollution. "In human terms, this would mean if your great-grandmother was exposed to an environmental toxin at a critical point in her pregnancy, you may have inherited the disease," says lead researcher Michael Skinner. "It is a new way to think about disease." And by "new" he means "freaky."