As scientists uncover more about genetics and a person's risk of many diseases, it's becoming increasingly clear that achieving and maintaining health is impacted by a common factor: your decisions.
This is good news for anyone who has a family history of obesity, diabetes, heart disease, cancer, asthma or other common disorders. By understanding your genetics, you may be able to use that information to guide your decisions, improve your well-being, and live a long and healthy life.
At the end of the day, you're born with your genes and all that has in store for you, including your chance of having several common health problems. Genetic testing can determine whether you have a higher risk of developing certain diseases. But just having a genetic risk doesn't mean you'll get the disease.
Science continues to show that your decisions to eat well, exercise, manage stress and maintain a healthy weight can influence your genes and tip the odds in overcoming your genetic tendencies.
Common medical conditions like obesity, heart disease and type 2 diabetes don't have a single genetic cause. Instead, they're usually the result of small changes, called variants, on multiple genes, combined with lifestyle and environmental factors. Health conditions with multiple causes are called complex (multifactorial) disorders.
Some diseases do have a single genetic cause. For example, everyone has a gene called cystic fibrosis transmembrane conductance regulator (CFTR). But only people who inherit two copies of a mutation on the CFTR gene — one from each parent — have cystic fibrosis. In those cases, a healthy lifestyle can't protect you or an unborn child from developing the disease.
But if a complex disorder runs in your family, you may have a genetic tendency that can be influenced — for better or worse — by the way you live your life.
An area of science, called epigenomics, studies how different environmental and lifestyle factors can alter how genes behave, without actually changing your genetic makeup. Factors like diet, toxin exposure, physical activity and stress can turn genes "on" or "off" and greatly impact your health.
Your genes are turned on and off throughout your life because of a process called gene regulation. Each cell turns on (expresses) only some of its genes. The rest of the genes are turned off (repressed). When a gene is turned off, it doesn't provide your body the instructions for making specific proteins. Proteins are programmed by your genes to do everything from make your eye color to attack invading viruses.
Some genetic changes are common, like becoming lactose intolerant as you age. In fact, about 65 percent of people have problems digesting milk products after infancy. Babies and young children have an active lactase (LCT) gene that provides instructions for making an enzyme called lactase. This enzyme helps you digest lactose, a sugar found in dairy products. But over time, the gene can get turned off.
Gene regulation isn't necessarily bad. It allows cells to react quickly to changes in the environment and protect you from cancer. Much research is underway to determine how lifestyle factors can turn genes on or off and the role that plays in developing — and fighting — cancer, diabetes, Alzheimer's disease and other conditions.
Deoxyribonucleic acid (DNA) is a special code of instructions that tells your genes what to do. It might surprise you to learn that 99.9 percent of DNA is the same for all humans. It's the 0.1 percent in your DNA that makes you an individual. Genetic variations (variants) are the differences in DNA code that make each person unique, like eye color, height and blood type.
Some variants even influence your taste buds, the foods you like to eat and how well you metabolize certain nutrients. One study found that gene variants account for about a third of the difference in how much sweetness people taste in sugar and low-calorie sweeteners.
Many doctors hope to one day use genetic information to diagnose, treat, cure and prevent illnesses. Medicine in the future might be tailored to genetic traits you've inherited from your family, your daily habits and the environment in which you live.
In the meantime, as genetic testing becomes more affordable, more people may benefit from understanding their influence over genetics by improving their health habits.
One specific report set out to determine how people responded after getting their results from a direct-to-consumer genetic test. The report analyzed the results from 11 such studies. The analysis determined that 23 percent of participants made a positive lifestyle change after receiving their genetic results. More specifically, 12 percent of participants improved both diet and exercise practices, 19 percent quit smoking, and 7 percent had preventive health care checkups.
So even though you are your genes, your health is not necessarily beholden to your genetics. A decision to replace a cookie with an apple can help you turn the tide and overcome your risk of inheriting many health problems — and that's a reassuring thought.
© 1998-2020 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved.