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Our DNA Dimmer Switches: How Cuddling, Smoking and More Can Affect Gene Expression

by Get Science Staff

In the “nature vs. nurture” debate, those in the former camp believe that who we are, from our physical traits to our propensity for disease, is largely predetermined by the genes that we inheritfrom our parents. The nurture side attributes much of who we are to our environment.  

Recent research shows that this age-old debate is far too simplistic. Nearly every cell in the body contains complete identical copies of our DNA—the body’s instruction booklet for some 20,000 genes. But what exactly determines which of these genes are expressed and which ones are not? While the body’s master instruction booklet can tell us a lot about who we are, how this book gets interpreted may tell us even more. 

The rising field of epigenetics seeks to answer these questions. Sure, we’re all born with a predetermined set of genes, but a variety of factors from exposure to environmental toxins to how much we're cuddled as a baby can influence how these genes are expressed. A growing body of research suggests that epigenetics can influence whether we develop diseases such as cancer or lupus, and plays a role in development of our personality and mental health. 

The Instructions of Life ‘on Top of’ Our DNA 

The field of epigenetics was first established in 1942 by British developmental biologist Conrad Waddington, who was fascinated by how biochemistry influences how genes are expressed. The term “epigenetic,” which literally means “in addition” or “on top of” genetics, refers to a variety of biochemical changes that occur on the outer surface of DNA or on packaging proteins around which DNA is wrapped that turn gene expression on or off. Such biochemical modifications can be inherited and can remain in place as cells divide, but external influences can affect these processes, too, in negative and positive ways: Physical exercise can increase the expression of genes involved in tumor suppression, for instance.  

In 2015, more than a decade after the entire human genome was first mapped, the “Roadmap Epigenomics Program (REP)” unveiled maps for the epigenomes of 111 different cell and tissue types. This complex data set identified epigenomic patterns associated with a variety of traits, from blood pressure and cholesterol to our propensity for Alzheimer's disease.