In Mayo Clinic Health Letter, we try to write about a spectrum of topics, from cutting edge advances in science to the most common medical maladies you are likely to encounter on a day-to-day basis.

This month, we bring you a leading edge article on "Epigenetics" — the science of how our genes are influenced by environmental factors in ways that turn them on and off to determine what characteristics and programs within the genetic code are activated. We explain some of the basics of how this works —how different mechanisms that are now coming to light activate and deactivate parts of our genetic program. This is a very optimistic and important area of new development.