What Is Epigenetics?

I have heard a little about "epigenetics" and how the genes of even great-grandparents can affect their descendants. But it seems complicated — can you explain the basics?
– Leona

Transgenerational epigenetic inheritance — or epigenetics, for short — doesn't exactly roll off the tongue. Yet this idea that environmental factors (such as diet, lifestyle choices and behaviors, and stress) can change the health not only of the people who are exposed to them, but also the health of their descendants, is something we'll be hearing more and more about.

Epigenetic experts believe that the environmental conditions and life experiences of parents, grandparents, and even great-grandparents can, in a way, flip "on/off switches" on the genes in their eggs and sperm, or the genes of fetuses in pregnant women, thus changing the genetic code of their offspring and descendants. In this way, new genetic traits can appear in a single generation, and be passed on to kids, grandkids, and beyond.

For example:

• Evidence suggests that smoking and overeating can affect genes, causing those affecting obesity to become "switched on" and those carrying messages for longevity to become "switched off."
  
  That means that besides the self-harm that can come from eating too much or smoking, these lifestyle choices may put a person's offspring (and even future descendants) at risk for disease and premature death.

According to traditional genetics, major changes in the structure of the human genome only happened over many generations or even thousands of years. But now, the concept of epigenetics is shedding new light on how such changes can happen much faster.

What Does This Mean for Families?

So is epigenetics just a topic of interest to scientists, or should it affect the way we live now? Growing research seems to support the role of parental lifestyles and their (possibly permanent) effects on the health of their children, grandchildren, and beyond.

While you may not be able to undo the genetic "on/off switch" changes you've passed on to the kids you already have, living healthier now could be invaluable to the health of your future offspring — and their kids. Epigenetics doesn't just apply to passing on potentially negative traits or health risks, but also to the benefits of inheriting healthy factors.

Scientists also are using the concept of epigenetics to develop new approaches to diseases with genetic roots. Drugs are now being made that act by switching on or off faulty genes in epigenetic fashion. This type of genetic "quick fix" could be a very valuable strategy in the fight to prevent, treat, or cure a number of conditions, such as cancer, diabetes, and Alzheimer's disease.