By Candida Fink, Joe Kraynak

Epigenetics is the study of changes that affect how genes are expressed without affecting the genes themselves. These changes occur through a variety of chemical interactions with the DNA. Sometimes these changes in expression occur as part of typical development and function, but some changes can disrupt normal processes and healthy cell function.

The science of epigenetics helps to explain the interplay between nature and nurture — how an organism’s genotype (genetic makeup) interacts with the environment to produce the organism’s phenotype (observable characteristics).

External events such as parental neglect or other trauma or stress may trigger chemical changes to DNA, which affect how a person’s genes are expressed. And these changes can pass to the next generation. So, for example, if an expectant mom has been exposed to chronic stress that has affected her mood-related genes, then the stress effect on the gene (not just the gene itself) can be passed on to her child. As a result, the child’s own genes as well as the effects of long-term stress on her mother’s genes affect the child’s likelihood of eventually exhibiting depression or other mood disorders.