In labs around the world, unusual mice scuttle around their cages. Half of each mouse’s tail is coated with fur the shade of burnt toast, while the tip is drained of color. It’s a telltale sign of variations in a gene called kit, yet these mice don’t carry mutations associated with the color mismatch in either of their alleles. Their parents, however, each harbored one mutated copy and have somehow passed a genetic memory on to their litter.
Heritable traits unexplained by genetic sequences are known to occur epigenetically—for example, through the accumulation of molecular caps on DNA that alter gene expression. Typically, researchers have focused on how environmental factors, such as parental stress and malnutrition, alter the epigenetic profile of their offspring. But epigenetic changes might also be guided by the mutations in a parent’s genome, says Didier Stainier, a developmental geneticist at the Max Planck Institute for Heart ...
