Genetics and Health: What Percentage of Diseases Are Genetic?

Discovering you have certain genes that predispose you to life-changing conditions—such as diabetes, dementia, or cancer—can make you feel like you have no control over your future health. But what percentage of diseases are genetic?

While you can’t change your genes, genes are just part of what has an impact on our risk of developing disease. And it turns out, they’re far from the biggest part. In this article, we’ll review some of the science regarding certain genes and diseases and the environmental factors that can have a large impact on whether or not your genes become your destiny.

Is health genetic?

Genes account for about 10 percent of human disease but the vast majority, the other 90 percent of our risk of disease, is determined by our environment—including modifiable lifestyle behaviors such as our nutrition, stress levels, sleep habits , and physical activity.

Today, few scientists believe that there is a singular gene entirely responsible for any one illness. Almost all inherited traits are the products of complex interactions of numerous genes and numerous external factors. Think of your genes as the keys that make up your internal piano, the music that’s played by each key pushed is the result of the interplay of many individual aspects of your environment. Essentially, the expression of these genes—if they are “switched” on or off or if the keys are “played” or not—can be affected, positively and negatively, in large part by our behaviors. Here’s how top lifestyle factors impact your disease risk along with your genetics.

Nutrition’s powerful impact on your disease risk

The science: Research indicates that a poor diet can have a significant impact on our chances of developing a wide range of diseases including heart disease, stroke, and type 2 diabetes (T2DM). Aside from our genetic makeup, when our body lacks essential vitamins and minerals because of a nutrient-poor diet, it directly impacts our immune function and leaves us more vulnerable to oxidative stress and inflammation and ultimately, more susceptible to illness.

One of the most well-known diet-related diseases is type 2 diabetes. While nutritional intake is far from the only factor that impacts T2DM development —research shows that age, genes, race, physical activity, and smoking can all play a role—a diet rich in refined carbohydrates, inflammatory fats, and preservatives and lacking adequate fiber , antioxidants, vitamins, and minerals can significantly contribute to insulin resistance , the most common cause of type 2 diabetes.

Researchers know that you can inherit a risk for type 2 diabetes and studies have identified about 40 genetic variants that can significantly predict T2DM, however, individually, most variants increase the odds of developing type 2 diabetes only by about 5 to 15 percent . This means that despite known genes associated with T2DM, lifestyle factors, especially including nutrition and maintaining a healthy weight, can have a direct impact on determining whether or not these genes “switch on” or not.

The strategy: You want to optimize your diet to ensure your body has the full spectrum of nutrients to defend against disease by including a wide variety of whole foods including an emphasis on colorful fruits and vegetables, nuts, seeds, well-sourced plant and animal proteins, and limited refined carbohydrates from breads, baked goods, sugar-sweetened beverages, and grains. Maintaining a healthy weight (classified clinically as a BMI between 18.5 and 24.9) can also decrease the risk of diabetes and other chronic illnesses while also reducing systemic inflammation that can contribute to disease. If you need help getting started, health coaches at Parsley Health can help guide you through an individualized nutrition plan that fits your needs, with both your genes and lifestyle in mind.

How sleep deprivation can hurt your genes

The science: When it comes to optimizing our lifestyle to improve our health and support healthy gene expression, sleep is a key factor in the equation. Sleep is involved in the healing and repair of tissue throughout the body and without this nightly “clean up” mechanism, internal homeostasis can be disrupted, leading to dysfunction and ultimately disease. Sleep deprivation is associated with decreased DNA repair and more breaks in DNA, potentially “switching on” unwanted genetic expression.

Research indicates that sleep deprivation has been linked to neurodegenerative diseases such as Alzheimer’s. While early-onset and late-onset Alzheimer’s disease involve different gene mutations , such as the APOE and PSEN genes, both variations of the disease result in an entanglement of specific proteins in the brain called tau proteins and beta-amyloid plaques that form clumps between neurons, leading to cognitive decline. Research shows that inadequate sleep increases levels of these tau proteins and accelerates the spread of these toxic clumps throughout the brain. Even more alarming, in another study, losing just one night of sleep led to an increase in beta-amyloid—suggesting that chronic sleep deprivation may increase the risk for long-term beta-amyloid build-up in the brain.

The strategy: Consistently opt for a goal of 7 to 8 hours of sleep per night. While less than seven hours can cause sleep deprivation and contribute to chronic disease, studies also show that habitually sleeping more than nine hours is associated with poor health. If you have trouble catching enough z’s, try to incorporate a nightly wind down routine that helps prepare your body for a good night’s rest. This may include dimming the lights, taking a hot shower or bath, listening to music, reading, and turning off screens and electronics 30-60 minutes prior to bedtime. If you feel you’re getting excess sleep and still constantly feeling fatigued, an underlying issue could be at play. Consider talking to a healthcare professional. Whether you’re sleeping too little or not enough, Parsley Health’s team of providers can dig deeper through comprehensive lab testing to determine the underlying cause. Parsley’s health coaches can help individualize care plans that include resources for best sleep practices.

Why physical activity can trump your genetics

The science: A sedentary lifestyle has a direct impact on our metabolic health—contributing to inflammation and weight gain, well-studied precursors of almost all chronic diseases. In fact, research shows that those who spent more than 23 hours sitting per week , whether in a car or in front of a screen, compared to those who spent less than 11 hours a week sitting had a 64 percent greater risk of dying from cardiovascular disease (CVD).

Despite numerous genes that have been found to be associated with an increased risk of CVD, an unhealthy lifestyle—including the known risk factor of physical inactivity—is a bigger contributor to heart disease than genetics, according to a study from the European Society of Cardiology .

The strategy: Aim for a goal of at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity a week, or a combo of both. Weight training and resistance work are also essential. Studies show that for every 10 percent increase in skeletal muscle mass, individuals experience an 11 percent reduction in risk of insulin resistance and a 12 percent drop in the risk of developing diabetes. It’s best to spread out your exercise over the course of your week to make it a more consistent and regular part of your routine . Greater amounts of exercise than those listed above will provide even greater health benefits. Our team at Parsley Health can help hold you accountable for building upon your physical activity goals to ensure they’re cemented into your weekly routine.

The reason stress has power over your genes

The science: Stress can make you sick. In fact, chronic stress seems to worsen or increase the risk of a multitude of conditions such as obesity , cardiovascular disease , Alzheimer’s , depression , digestive issues , autoimmune diseases , and asthma . When it comes to our genetic predisposition to disease, stress is a key factor that can create an internal environment that encourages disease-related genetic variants to “turn on” and start to express themselves.

A well-documented example of this is celiac disease. Celiac disease—an autoimmune condition that occurs when an individual has an immune reaction to eating gluten —can become active in some individuals after an intense period of stress such as surgery, pregnancy, childbirth, viral infection, or severe emotional stress. While around 30 percent of the overall population has one or both of the celiac disease genes, HLA DQ2 and HLA DQ8, only around 3 percent of the population go on to develop celiac disease—underscoring the large part environmental factors such as stress play in affecting if the disease ultimately surfaces or not.

Even outside of celiac disease, stress is universally inflammatory to the body and overtime chronic inflammation from persistent stress can cause dysfunction—leading to disease.

The strategy: Managing your stress can make a big difference between illness and health. Incorporating regular stress reduction techniques into your daily routine is essential to reducing internal inflammation and suppressing unwanted genetic expression. Take the time to really explore different stress management tools such as meditation , deep breathing, journaling, writing, singing, or exercising. Implementing an activity that you enjoy that helps you to find balance and that you look forward to engaging with is a key component to ensuring you remain consistent.

What you can do to take control of your health, despite genetics

Your genes are a part of you, but they’re not all of you. Adopting health-promoting behaviors that support your overall wellness can help to positively influence your genetic code. At Parsley Health, we support our members in understanding their inherited risk of disease by guiding them through genetic testing results and providing them tools to help prevent illness. We find there is real empowerment in helping teach our members that our environment, and not our fixed DNA, is the primary driver of our future health, giving us more control than we think in paving the way for a healthy path forward.

Takeaways

With so many aspects to optimize, our doctors and health coaches begin by creating goals around the foundational pieces of health including improving nutrition, physical activity, sleep hygiene, and stress management in addition to recommending in-depth testing, targeted supplementation, and medication as needed.

From there, we can help you assess other environmental influences that might be impacting your health such as your exposure to heavy metals and mold or toxins that may be hiding in your personal care products , tap water, home environment, or food choices. To learn more, contact Parsley Health today.