Hello Muddah, Hello Fadduh

The New York Times' Nicholas Wade examines genetic imprinting, in what he calls a "tug of war" between the mother's and father's contributions to a fetus. Until recently, Wade notes, about 100 imprinted genes were known. According to research published in Science in July by Harvard's Christopher Gregg and colleagues, there are nearly 1,300 genes imprinted in mice. According to study co-author Catherine Dulac, it's likely that a "substantial, though lesser, proportion to be imprinted in people — maybe some one percent of the genome." In the mouse brain, Gregg and Dulac et al. found that 347 genes "where either the mother's or the fathers copy was more actively expressed in certain regions," Wade reports, which the investigators attribute to evolutionary fitness and familial interests.