The nutritional sins of the mother… Prenatal exposures of a mother can affect the health of her offspring, but how? Radford et al. found that the male progeny of undernourished pregnant mice had altered DNA chemistry in their sperm. In addition, the offspring displayed compromised metabolic health. The specific affected genes not only lost DNA methylation but also lacked the normal sperm DNA packaging factors (protamines) and instead were enriched in nucleosomes. Thus, when subjected to a suboptimal prenatal environment, offspring feel the effects of the maternal assault. Science , this issue p. 10.1126/science.1255903