Epigenetics is defined as the study of the heritable changes in gene expression that are transmitted from a mother cell to a daughter cell or a parent to its progeny, that occur without modifications in DNA sequences. The epigenetic mechanisms of gene regulation include DNA methylation and post-translational modifications of histone tails such as acetylation. Generally speaking, the more methylated the DNA is, and the less acetylated the associated histones are, the less a gene will be expressed. Herein, we introduce the reader to the field of epigenetic reprogramming and its importance during embryonic development and gametogenesis. We also summarize the current litterature on environmental influences on epigenetic processes including the epigenetic transgenerational actions of endocrine disruptors and diet.