Mechanisms of transgenerational epigenetic inheritance: lessons from animal model organisms

Epigenetic inheritance is a phenomenon whereby stochastic or signal-induced changes to parental germline epigenome modulate phenotypic output in one or more subsequent generations, independently of mutations in the genomic DNA. While the number of reported epigenetic inheritance phenomena across phyla is exponentially growing, much remains to be elucidated about their mechanistic underpinnings, and their significance for organismal homeostasis and adaptation. Here, we review the most recent epigenetic inheritance examples in animal models, outlining molecular details behind environmental sensing by the germline, and the functional relationships connecting epigenetic mechanisms and phenotypic traits after fertilization. We touch upon the experimental challenges associated with studying the scope of environmental input on phenotypic outcomes between generations. Finally, we discuss the implications of mechanistic findings from model organisms for the emergent examples of parental effects in human populations.