Describe epigenesis and the role epigenetic research plays in understanding the relationship between heredity and environment. Include an example that illustrates this role.

Question

What will be an ideal response?

Answer 1

Epigenesis views human development as a bidirectional relationship between genes and the environment. That is, genes play a role in behavior and experiences, but, equally important, behavior and experiences also affect gene expression. This environmental modification of gene expression can occur at any age, with both positive and negative effects.
Epigenetic research focuses largely on methylation, a biochemical process triggered by certain experiences, in which a set of chemical compounds lands on top of a gene and changes its impact, reducing or silencing its expression. For example, one study examined the potential role of methylation in post-traumatic stress disorder (PTSD) and depression. Participants were Tutsi mothers who had been pregnant during the Rwandan genocide and their adolescent children. Half of the mothers had been directly exposed to the trauma, and half had been outside the country at the time. Findings indicated substantially higher PTSD and depression scores among not only the mothers who had experienced the trauma but also their children. The mothers also displayed greater methylation of a chromosome-5 gene that plays a role in stress-hormone regulation. Moreover, the children of the trauma-exposed mothers also displayed higher gene methylation.
Although this study leaves open the possibility that other environmental influences played a role in the elevated methylation levels, it nonetheless offers convincing evidence that the effects of maternal trauma can induce epigenetic changes in children, with lasting consequences for development.