How your genes affect your health: what you need to know

Many people seem to think that the reason I’m fit and well is because of my genes. The reason I am fit and healthy is partly down to my genes, but is also down to the way I eat, the amount of exercise I take, and my enthusiasm and participation in life. It’s partly down to luck. I’ve had many great things happen in my life. But genes and luck don’t explain everything about my health and well-being. Genes and luck don’t explain everything about your level of health and well-being.

Some people do have an increased risk of some illnesses (such as some cancers, type 2 diabetes and frontotemporal dementia), because they have an inherited gene fault. Even in these situations, the development of that specific illness may not be inevitable, or it may be that there are things you can do to delay onset.

Genes and disease risks

Researchers at the University of Alberta (Canada) reviewed all the main studies over the last 20 years examining the relationships between common gene mutations and different diseases and conditions. They concluded:

“In most cases, your genes have less than five per cent to do with your risk of developing a particular disease.”

They go on to say:

“It is becoming increasingly clear that the risks for getting most diseases arise from your metabolism, your environment, your lifestyle, or your exposure to various kinds of nutrients, chemicals, bacteria, or viruses.”

The website Genes In Life says:

“You can’t change your genes, but you can change your behavior. There are steps you can take to prevent disease, lower your risk, and find problems early when most treatments work best.”

Professor Dean Ornish is the president and founder of the non-profit Preventive Medicine Research Institute in Sausalito, California (USA). He says:

“Your genes are not your fate… if you change your lifestyle, you change your genes.”

Your epigenome

The epigenome refers to a set of chemical modifications that can occur on your DNA and its surrounding proteins, without actually changing the underlying genetic code. You still have the same genes, but the epigenome turns the gene on or off, and so influence various aspects of your health.

While your DNA provides the blueprint for your body’s structure and function, the epigenome can act as a kind of “interpreter,” helping to translate your genetic information into actual traits and behaviours. These modifications can be influenced by a variety of factors, including your environment, diet, stress levels, and even your experiences and behaviours.

A study from Washington State University (USA) followed 70 pairs of identical twins from 2012 to 2019. It found that the more physically active siblings had lower signs of metabolic disease, measured by waist size and body mass index. This also correlated with differences in their epigenomes. The more active twins had epigenetic marks linked to lowered metabolic syndrome, reducing the risk of heart disease, stroke and type 2 diabetes.

Because the twins were identical and had the same genes this is important evidence that a healthy lifestyle influences health outcomes. If genetics and DNA sequence were the only drivers for biology, then essentially twins should have the same diseases. But they don’t necessarily.

Genes and old age

People often get sicker as they grow older, but research from Gil McVean of the University of Oxford (UK) and colleagues finds that the impact of a person’s genes on their risk of getting sick actually wanes with age. McVean says:

“Our work shows that the way in which genetics affects your risk of getting a disease change throughout life. For many diseases, genetic factors are most important in determining whether you will get a disease early in life, while – as you age – other factors come to dominate risk.”

This understanding has also been supported by work from researchers at UC Berkeley (USA). They found:

“ … while our individual genetic makeup can help predict gene expression when we are younger, it is less useful in predicting which genes are ramped up or down when we’re older [more than 55 years old] … Identical twins, for example, have the same set of genes, but as they age, their gene expression profiles diverge, meaning that twins can age much differently from each other.”

Isn’t that a cheering thought? Your genes are (and will) continue to have less and less influence on your health as you age. It’s more and more down to you. Oh, that may be a scary thought, but I aim to help you out. I want you to see this as a time of opportunity.

Genes and cancer

Cancer Research UK says:

“As well as a gene fault, many other factors need to be in place for a cancer to develop. Because the other factors are not always in place, the cancer may seem to skip a generation. A parent may have the gene and not develop cancer but their child who inherits the same gene does develop cancer.”

So there you have it. Don’t assume you can’t do anything about your health because of your genes. A healthy lifestyle can result in better health across a whole range of illnesses.