Within the last century, researchers’ understanding of genetics has undergone a profound transformation.

Genes, regions of DNA that are largely responsible for our physical characteristics, were considered unchanging under the original model of genetics pioneered by biologist Gregor Mendel in 1865. That is, genes were thought to be largely unaffected by a person’s environment.

The emergence of the field of epigenetics in 1942 shattered this notion.

Epigenetics refers to shifts in gene expression that occur without changes to the DNA sequence. Some epigenetic changes are an aspect of cell function, such as those associated with aging.

However, environmental factors also affect the functions of genes, meaning people’s behaviors affect their genetics. For instance, identical twins develop from a single fertilized egg, and as a result, they share the same genetic makeup. However, as the twins age, their appearances may differ due to distinct environmental exposures. One twin may eat a healthy balanced diet, whereas the other may eat an unhealthy diet, resulting in differences in the expression of their genes that play a role in obesity, helping the former twin have lower body fat percentage.

People don’t have much control over some of these factors, such as air quality. Other factors, though, are more in a person’s control: physical activity, smoking, stress, drug use and exposure to pollution, such as that coming from plastics, pesticides and burning fossil fuels, including car exhaust.

Another factor is nutrition, which has given rise to the subfield of nutritional epigenetics. This discipline is concerned with the notions that “you are what you eat” – and “you are what your grandmother ate.” In short, nutritional epigenetics is the study of how your diet, and the diet of your parents and grandparents, affects your genes. As the dietary choices a person makes today affects the genetics of their future children, epigenetics may provide motivation for making better dietary choices.

Two of us work in the epigenetics field. The other studies how diet and lifestyle choices can help keep people healthy. Our research team is comprised of fathers, so our work in this field only enhances our already intimate familiarity with the transformative power of parenthood.

The roots of nutritional epigenetics research can be traced back to a poignant chapter in history – the Dutch Hunger Winter in the final stages of World War II.

During the Nazi occupation of the Netherlands, the population was forced to live on rations of 400 to 800 kilocalories per day, a far cry from the typical 2,000-kilocalorie diet used as a standard by the Food and Drug Administration. As a result, some 20,000 people died and 4.5 million were malnourished.

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