Is Your DNA Your Destiny? A Primer on Epigenetics
NATURE VS. NURTURE. It’s among the oldest of philosophical and scientific debates. Is your inherited genetic makeup your destiny? Or are you the product of your environment?
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As a geneticist, I can say with confidence that we are an intricate and still mysterious combination of both. We can now map your genome, the complete set of inherited DNA that exists in every cell of your body. We can identify specific genetic factors in disease. We also know that genes can change or mutate, sometimes spontaneously, sometimes as the result of environmental stressors, to cause diseases like cancer.
But an enduring mystery is why genes don’t always “express,” or turn on. Why do patients with genes that seem to predispose them to cancer and other diseases often escape what might seem to have been their genetic destiny?
The science of epigenetics is an intriguing attempt to answer that and related questions. “Epi” is Greek for “above,” and epigenetics is the study of information in the cell, over and above the genome, that activates or deactivates genes. Epigenetics attempts to explain processes inside the cell that could account for the differences between identical twins, for instance, or for the fact that a nerve cell is so different from a blood cell even though they contain exactly the same genetic information.
Mapping the Human Epigenome
Just as we have mapped the human genome, scientists at the National Human Genome Research Institute have an even more ambitious goal: to map the human epigenome, the multitude of chemical compounds and proteins that attach to the DNA and tell the genes what to do. The challenge is that there is no single human epigenome. It’s different in different people and different cells, and it changes over time. So, scientists are mapping multiple tissue types, including various types of cancer.
When epigenomic compounds attach to DNA, they are said to have “marked” the genome. These marks can be passed on with the DNA from cell to cell as cells divide, and possibly even from parents to children.
How Can Epigenetics Be Used?
Epigenetics is a hot topic in medical research, especially in the quest for therapies targeted to specific types of tumors and other genetic illnesses. Still, there are no medical applications on the immediate horizon. The problem is that the impact of epigenetic processes is extremely broad and difficult to define, so interfering with them could have serious unintended consequences, including actually promoting cancer.
Epigenetics, and perhaps the hope that we might have some control over our genetic destiny, is also a hot topic in popular culture. Some health practitioners recommend methylation supplements based on dubious theories about how methylation works and its supposed impact on a wide range of health issues. These supplements are probably, at best, a waste of money. And like all unregulated supplements, they could have unintended negative consequences.
Epigenetics researchers seem to agree that the epigenome is resilient and well equipped to respond to the stresses of human life. But lifestyle and environmental factors like smoking, disease, stress and even age may trigger the chemical responses that could, in turn, affect the genome.
The healthiest response to the overarching lesson of this emerging science – that lifestyle and environmental factors can have lasting impacts on gene expression – would be to do all of the things that we already know promote long-term health, including eating well, maintaining a healthy weight, exercising and finding ways to lead a low-stress, mindful and joyous life.