Germ cell development involves the most extensive epigenetic remodelling of any in-vivo cell type, but the mechanisms remain poorly understood. Disruptions in these processes may result in the introduction of germline epimutations that alter transcriptional control and development in germ cells, and in the parent’s offspring. We are disrupting function of epigenetic modifiers in ex-vivo organ culture and in-vivo mouse models, with the aim of providing insights into the role of epigenetic mechanisms in development and epigenetic patterning of the germline. Our data indicate that the essential epigenetic modifier, Polycomb Repressive Complex 2 is essential for germ cell development, fertility and transcriptional control in the father’s offspring. These findings indicate that histone-modifying complexes contribute significantly to germline function and transmission of epigenetic information through the male germline. Greater understanding of epigenetic mechanisms in the developing germline is critical for determining how epigenetic defects in the germline influence germline transmission of epigentic information and the inheritance of complex disease in a parent’s offspring.