Transgenerational inheritance of non-genetically determined phenotypes.

Inheritance of non-genetic factors permits ancestral environmental history to inform the development of subsequent generations. This form of soft inheritance has been shown in mammals, yet the molecular underpinnings of this phenomenon are poorly understood. In the present article, we focus on gametic inheritance of non-genetic factors, utilizing examples of paternal transmission to explore the core issues that need to be addressed in order to gain greater insight into the molecular mechanisms. Three essential processes are identified: (i) how the environment affects the germline to establish an altered molecular milieu, (ii) the molecular nature of the inherited mark, and (iii) how this affects genome function in the developing embryo to elicit an alternative developmental outcome.