Environmental agents such as nutrition and chemical exposure can alter gene expression by affecting the epigenome. Epigenetic changes may also have important effects on behavior phenotypes. Which of these examples correctly describe explicit evidence supporting epigenetic traits as heritable?
a) The level of maternal nurturing that children receive results in distinctive epigenetic changes to the human nervous system that can be transmitted across generations.
b) Exposure of pregnant women to poor nutrition during famines affects their developing fetuses and has detrimental effects during adulthood and subsequent generations.
c) Feeding pregnant mice methylation precursors shifts the coat color of their offspring from yellow (unmethylated promoter) to pseudoagouti (highly methylated promoter).
d) The level of maternal nurturing in newborn rats causes differential gene expression that corresponds with stressed phenotypes that can be transmitted across generations.