By Andy Galpin, Ph.D. Director of the Biochemistry and Exercise Physiology Laboratory at California State University, Fullerton.
Go ahead and blame your parents. It’s true, a majority of who you are and how you function was predetermined by the genetic material you inherited when your father’s sperm implanted in your mother’s egg. Environment factors critically influence us as well. Thus, for centuries scientist described human variability as genetic heritability + environment influences. In other words, you = your genes + your lifestyle. This all changed in 2003 when the human genome was finally mapped.
We’ve all heard sayings like “only the strong survive”. This concept, outlined by Charles Darwin, suggests the organisms best fit (“strongest”) for the environment will survive best over time. The offspring of these animals are at an advantage as they possess the physical traits best suited for that environment (i.e. they inherit great genes). Animals lacking optimal genetic inheritance will need to adapt, or perish.
Humans are no different. Our bodies were built to adapt to environmental stressors. Our cells constantly accrue damage during the normal living process. These malfunctioning cells need removal and replacement with identical, fully-operational replicas. We accomplish this maintenance by identifying the portion of our DNA (called a “gene”) that makes the damaged cell. The targeted gene is “expressed” resulting in the building of the exact right cell. Gene expression has received extensive scientific study over the last 3+ decades. However, only lately have scientists realized the expression of your genes changes throughout your lifetime (epigenetics).
Epigenetics is arguably the hottest topic in Physiology right now, but the research is in its infancy and many important questions remain. Nonetheless, the available evidence clearly shows that lifestyle choices like exercise, nutrition, and sleep significantly affect the genes responsible for numerous physiological adaptations (e.g., energy utilization, mitochondrial density, etc.). The idea that your exercise habits change the way your DNA is express was both shocking and exciting.
Even more surprising was the realization that epigenetic changes are inherited by your offspring! A recent study provided the first evidence that exercise training regulates and changes the epigenetic profile in the sperm of healthy men. So while part of you was predetermined, a part of your children is determined by your lifestyle. You were built to handle and adapt to challenges. Never forget that, and never stop challenging. You = your lifestyle. Your lifestyle = the genes your children inherit.