Approach to Connecting Ancestral Exposures to Descendants’ Phenotypes Through Germ Cell Modifications. a In humans, no single study has demonstrated a connection in which an exposure leads to a germ cell modification, ultimately manifesting as a disease or phenotype in descendants. Various exposures (food, cigarette smoking, in utero thyroid hormone exposure, stress, etc.) have been associated with changes in germ cell epigenetic processes (1); exposures have also been associated with diseases in children and grandchildren (3). Less commonly, a disease has been associated with germ cell abnormalities in anindividual’s parents (2). b Table summarizing specific findings regarding the associations described in (a).