Estrogen-mimicking pollutants can trigger gender-bending effects in wildlife. For instance, male fish exposed to such hormonally active pollutants will make vitellogenin, an egg-yolk protein that’s normally fashioned only by females (SN: 1/8/94, p. 24: http://new.sciencenews.org/sn_edpik/ls_7.htm). A new study finds that once initially spurred to make vitellogenin, males don’t need a steady bath of estrogen to maintain high levels of the motherly protein.