The course will delve into the significance of the epigenome and its contribution to behavioral and physiological traits of exposed individuals and their progeny. Particular focus will be placed on epigenetic factors linked to trauma and stress, with an emphasis on their investigation in mouse models and the latest research on the potential mechanisms underlying epigenetic inheritance, shedding light on this groundbreaking shift in our understanding of heredity.

Innate traits, fundamental to an individual's identity, are determined by the genetic material inherited from parents through reproductive cells, namely oocytes and spermatozoa. This genetic blueprint, encoded in the intricate structure of DNA, resides within the nucleus and mitochondria of cells. Among the vast sequence of DNA, only 1-2% comprises genes, specific sequences responsible for encoding proteins. The remaining 98-99% of DNA consist of noncoding sequences positioned between genes. Though not protein-coding, these DNA sequences can be transcribed into RNA called non-coding RNA that exerts critical regulatory functions in cells. While the genetic code is pivotal for individual identity, it does not stand alone in shaping our features. Equally important is the epigenetic code, a parallel and complementary layer of individual information essential for biological functions.

The epigenetic code or epigenome, often described as non-genetic, is an assembly of modifications and markers located both, on and around DNA, that intricately orchestrate gene activity and regulate sequences nestled between genes. Epigenetic marks are multiple, multifaceted and dynamic and together, constitute a code that is highly complex (more complex than the DNA sequence itself). Epigenetic factors and marks work in concert with the DNA to regulate cellular processes during development and adulthood. Epigenetic marks manifest through biochemical modifications to DNA itself such as cytosine methylation and to histone proteins associated with DNA including acetylation, phosphorylation and methylation. Additionally, non-coding RNA, molecules synthesized from regulatory DNA sequences and present within the nucleus and cytoplasm of cells, play a pivotal role in this intricate system. Unlike the relatively stable DNA sequence, most epigenetic marks and non-coding RNA are highly dynamic and susceptible to changes induced by environmental factors and life experiences. In some cases, the changes can persist over time.

For a long time, it was believed that only innate traits can be inherited and passed down to offspring, owing to their association with genetic material transmitted from parents. In stark contrast, it was commonly assumed that acquired traits could solely develop during an individual's lifetime and were not inheritable. Recent investigations in both humans and animal models have challenged this notion, revealing that acquired traits can indeed be transmitted from parent to offspring, paralleling the inheritance of innate traits. This paradigm shift has profound implications for our understanding of health and disease, as life experiences, including traumatic events, exposure to violence, dietary habits, and exposure to endocrine disruptors, especially during childhood, are recognized to significantly impact mental and physical health of exposed individuals. The possibility that these effects can be inherited suggests that the health of children and even possibly grandchildren of exposed individuals may also be influenced.