Early life epigenetic programming and transmission of stress-induced traits in mammals: how and when can environmental factors influence traits and their transgenerational inheritance?

The environment can have a long-lasting influence on an individual's physiology and behavior. While some environmental conditions can be beneficial and result in adaptive responses, others can lead to pathological behaviors. Many studies have demonstrated that changes induced by the environment are expressed not only by the individuals directly exposed, but also by the offspring sometimes across multiple generations. Epigenetic alterations have been proposed as underlying mechanisms for such transmissible effects. Here, we review the most relevant literature on these changes and the developmental stages they affect the most. We discuss current evidence for transgenerational effects of prenatal and postnatal factors on bodily functions and behavioral responses, and the potential epigenetic mechanisms involved. We also discuss the need for a careful evaluation of the evolutionary importance with respect to health and disease, and possible directions for future research in the field.