But how does stress take its toll on the body? Advances in science have revealed some of the mysterious underlying processes that translate internal and external environmental influences into biological change. This figure illustrates 2 segments of DNA and two ways of changing DNA. We know that DNA influences all aspects of our development, our health and wellbeing. The image on the left shows one way this happens. There is a mutation or deletion that involves the loss of one nucleotide from the segment of DNA. This mutation changes the sequence of the code. We also know that cells read the code and then translate the code through complex biochemical processes into observable outcomes.

Now let’s look at the image on the right. In this case, something is attached to the DNA, specifically a methyl molecule or group of atoms, and this results in a chemical modification of DNA. Some scientists have called this ‘chemically decorating’ the DNA and this also influences the same developmental, observable outcomes.

The really important thing to remember is that this second kind modification, called epigenetic modification, does not change the sequence. It involves changes that are added to the sequence or are ‘above the genome.’ This kind of alteration happens as a result of environmental experience and exposure. It’s obvious that experience matters but these new discoveries explain how stressful experience, in particular, can alter our very genes and be a potent source of epigenetic programming.