A gene that guides the maternal care that female mice give their newborn pups also directs how a male learns to reproduce efficiently, researchers report. This same gene pushes a fetus to draw nutrients from the mother, even at the expense of her health.
A genetic battle of the sexes rages between mammalian parents. The gene called Peg3 is one of about 100 genes where the copy contributed to the offspring by one parent is switched off, leaving the other parent's copy active. Peg3 and others where the father's gene is active promote fetal growth at the expense of the mother's health. In contrast, when the mother's gene rules, it limits the embryo's growth and preserves the mother's energy.