Every single human has a completely different DNA structure. For some, it causes brown eyes; for others, it governs blue—but for some, it increases the likelihood that a malignant tumour starts growing within their colon.

Every human has a distinct DNA structure, but amazingly, the probability of an isolated defect is slim. In fact, the CDC states that only 10% of all contracted diseases come from genetics, with the remaining 90% being attributed to an individual’s environment.

As a result, we now have the study of epidemiology—non-genetic influences on disease proliferation—with pattern recognition in determinants of health conditions taking priority. Examples include obesity and sedentary lifestyles as risk factors for type 2 diabetes, endocrine disruptors contributing to hormonal imbalances, and hygiene playing a role in the spread of numerous viruses.

For this reason, it is vital that, as a society, we locate the most probable causes of human diseases and disorders, not only mentioning viruses and pathogens but also chronic, preventable conditions.

One of the most misconceived influences on disease formation is diet and exercise. In Western countries, cardiovascular disease (CVD), a completely preventable condition, accounts for 17.3 million deaths worldwide, or 31.5% of all fatalities. Additionally, 18% of deaths occur in individuals under 65—about 3.1 million annually. However, these deaths are mostly preventable. As understood within the scientific consensus, proper and well-curated nutrition and exercise are the most preventative factors against CVD deaths, making them the highest priority.

The same goes for type 2 diabetes. Obesity is believed to account for 85% of type 2 diabetes diagnoses, with individuals with a high BMI being 80 times more likely to face its effects. But, as with CVD, the most preventable method is diet and exercise.

When our body lacks essential vitamins, minerals, and macronutrients—usually due to a nutrient-poor diet—our body doesn’t have sufficient energy or signals to effectively maintain our immune function, risking inflammatory responses when attacking stressors, ultimately increasing susceptibility to various conditions.

Furthermore, individuals considered to have excess fat mass are correlated with insulin resistance. When cells are unable to uptake insulin effectively, it leads to elevated blood glucose levels, leaving glucose within the bloodstream instead of allowing it to be absorbed into the cells for energy, leading to increased adipose tissue storage. As a result, the pancreas produces more insulin to compensate, leading not only to higher insulin levels but also to the risk of further metabolic disturbances, such as dyslipidaemia (elevated lipid levels).

For this reason, maintaining a healthy BMI and consuming nutrient-rich foods helps prevent numerous chronic conditions and early deaths.

Next comes sleep. Sleep deprivation, characterised by inadequate duration and often compounded by poor quality, hinders the body’s ability to repair damage from the day. During our everyday lives, we experience many stressors. Sleep allows our body to recover from these stressors, enabling us to face them again tomorrow. This doesn’t have to come from physical exertion; it can also arise from mental or emotional strain. Whether it’s dealing with work-related issues, personal conflicts, or even digesting food, our brains and bodies need time to rest, process, and reset during sleep.

When an individual does not get enough sleep or high-quality sleep for an extended period, they run a higher risk of developing heart disease, diabetes, and weakened immunity, with even a correlation to obesity.

As we sleep, our body undergoes different stages, each of which has its own importance. Non-REM sleep, or deep sleep, is used to recover from physical exertion, while REM sleep is essential for mental and emotional regulation. Chronic deprivation of both types has been shown to lead to numerous preventable conditions.

In fact, sleep deprivation has been correlated with impaired cognitive performance, decreased DNA repair, depression and anxiety, and cardiovascular morbidity. Furthermore, cognitive decline can become so severe that it can cause neurodegenerative diseases such as Alzheimer’s.

We have seen neurodegenerative diseases skyrocket throughout our society, but the genetic versions are extremely rare. In fact, only a few thousand people have the genes that directly contribute to Alzheimer’s, and they typically start showing symptoms in their 40s and 50s. The other 54.9 million cases are classified as non-genetic, or in other words, environmentally influenced.

Therefore, while genetics play a role in the health we inherit, overwhelming evidence suggests that our lifestyle choices and environment significantly dictate the prevalence of disease in our lives. Studies in epidemiology show us that by addressing lifestyle factors—nutrition, physical activity, sleep, and managing environmental exposures—we can drastically reduce the leading causes of death and disability.

We must understand this and take accountability for our own demise.