Family Genes Determine the Lifestyle and Work Style That Suit Us Best

On the first day of the Lunar New Year this year, my third uncle passed away after unsuccessful treatment for colorectal cancer. Before the Mid-Autumn Festival, my son suddenly developed a perianal abscess triggered by diarrhea. Two days prior, my father had also suffered from diarrhea caused by enteritis.

Since childhood, I have known that our family carries a genetic vulnerability. Both my son and I are prone to diarrhea and are highly sensitive to food hygiene. Eating at home is fine, but dining out leads to diarrhea nine times out of ten. We often joke that we are “quality inspectors” for food hygiene, able to judge whether a restaurant is sanitary based on whether we get diarrhea afterward. My father and his brothers all share this issue, as do my male cousins.

Such familial clustering can only be attributed to genetics. However, my three eldest uncles are still alive and in excellent physical condition well into their eighties; some even continue to farm in the countryside. My father, approaching eighty, can still lift stones weighing over a hundred jin. Only my third uncle died of colorectal cancer, but he was already 75 when diagnosed and passed away at 77, an age close to China’s average life expectancy, which is projected to be 79 in 2025.

This indicates that while our family genes cause some inconvenience in daily life, they do not shorten our lifespan; in fact, my paternal family could be considered a long-lived lineage. Our diarrhea improves significantly with Bifidobacterium supplements and can even resolve on its own within days without medication. This hereditary intestinal issue is likely related to familial susceptibility in gut microbiota and a weaker intestinal barrier. We can rule out conditions like ulcerative colitis and Crohn’s disease, as the latter are virtually impossible to find in long-lived families.

Reflecting on my lifestyle over the years, I have favored a life of both farming and reading, cultivating not only vegetables but also many flowers and plants. My physical activity level is much higher than average, though not as high as my father’s generation. I rarely eat out and maintain a disciplined diet at home, so I haven’t experienced diarrhea in many years. I now suspect that our family’s inherited high level of self-discipline is linked to our enteritis genes—without such discipline, we simply cannot live normally.

Because I understand how to avoid triggers, I rarely develop symptoms despite carrying this gene, and my condition has become even more stable after the age of thirty. My father and his brothers have mostly stayed at home throughout their lives. Only my third uncle was a mason who frequently worked on construction sites in his youth, eating out often. Repeated irritation likely caused chronic intestinal inflammation, which may be one reason he developed colorectal cancer.

However, it is not solely those with this genetic predisposition who are prone to colorectal cancer. Human genetic variation is remarkably small; the difference between any two individuals is less than 0.1%. Unhealthy lifestyles can independently trigger related diseases, often with an even greater impact than genetics alone, though genetic factors do increase the probability of onset.

I once spoke with a colleague in Beijing who specializes in treating colorectal cancer. He mentioned that his department conducted a study on a nearby research institute with over 2,000 employees, among whom 15 were treated for colorectal cancer at their hospital within a five-year period. The high incidence rate was surprising.

This is closely tied to researchers’ lifestyles. As we know, scientific achievements are largely the result of long hours of sedentary work, which is detrimental to intestinal health. Consequently, researchers suffer from anorectal diseases at a disproportionately high rate.

This week, I took my son to Beijing People’s Hospital for treatment of an anorectal condition. I discussed the triggers for my son’s case and how to reduce the recurrence rate with his attending physician.

He told me that cases like my son’s are extremely common among universities and research institutions near the hospital. The area is densely populated with top-tier universities (including 985, 211, and Double First-Class institutions) whose students typically score above 600 in the national college entrance exam and study exceptionally hard.

Beijing People’s Hospital serves as the designated medical insurance provider for these institutions. The gastroenterological surgeon sees so many patients daily that he is overwhelmed. He attributes their anorectal diseases primarily to prolonged sitting and believes this demographic finds it extremely difficult to change their lifestyle.

Insights from these two clinicians, who deal most frequently with anorectal diseases, made me realize that in specific populations—such as those in higher education and research institutions—the incidence of both common intestinal diseases and colorectal cancer is significantly elevated. This is not merely a result of genetics but is primarily driven by lifestyle.

Genetic factors rarely act alone; they typically interact with lifestyle to trigger disease. Even if one inherits genes associated with poor health outcomes, avoiding unhealthy lifestyle choices can keep the incidence rate very low or even prevent the disease entirely.

When I took Medical Genetics, my professor emphasized that virtually everyone inherits at least four or five susceptibility genes that can predispose individuals to various diseases.

With advances in molecular biology and human genetic engineering, we may one day be able to identify each person’s susceptibility genes through genetic testing. Such a report could guide us in avoiding the accumulation of other pathogenic risk factors, thereby preventing various familial diseases.

We can also analyze prevalent diseases within our own families to infer whether we carry certain susceptibility genes, and then develop more scientific, targeted strategies to prevent specific conditions.

People commonly take psychological assessments to determine suitable careers. In my view, we should also pay greater attention to how our genetic makeup influences our choice of lifelong vocation.

For instance, if we carry genes predisposing us to colorectal cancer but choose a sedentary job, we are exposed to two high-risk factors for cancer. If we also prefer meat over fruits and vegetables, we add a third high-risk factor. Each additional high-risk factor significantly increases the probability of developing colorectal cancer.

Similarly, individuals carrying genetic markers for lung cancer who smoke are already exposed to two high-risk factors for the disease. If they also work in environments with prolonged exposure to dust or asbestos, or live in areas with severe air pollution, their risk of developing lung cancer escalates further.

Of course, this principle extends beyond genetic factors to other pathogenic elements. For example, a hepatitis B patient carries the hepatitis B virus, which is a high-risk factor for liver cancer and cirrhosis. If such a person chooses a job that requires frequent alcohol consumption, they add another high-risk factor for liver cancer. If they also habitually stay up late and overexert themselves, yet another high-risk factor is added. The accumulation of multiple high-risk factors dramatically increases both the likelihood of developing liver cancer and the probability of onset at a younger age.

Every poor health decision we make will eventually exact a heavy toll. I have seen many people remain indifferent before falling ill, simply because they have not yet experienced the agony of disease. Once they become sick, their reaction is invariably profound regret. Rather than regretting it when it is too late, it is far better to make the right choices from the very beginning.