Family Genes Determine the Lifestyle and Work Best Suited to Us

On the first day of the Lunar New Year this year, my third uncle died of colorectal cancer despite treatment. Just before the Mid-Autumn Festival, my son suddenly developed a perianal abscess, triggered by diarrhea; two days earlier, my own father had also had diarrhea from enteritis.

From childhood I have known that our family genes have a certain flaw. Both my son and I get diarrhea easily and are very particular about food hygiene. Eating at home is fine, but eating out causes diarrhea nine times out of ten. We often joke that we are food-hygiene inspectors: we can tell whether a restaurant is clean by whether we get diarrhea afterward. Several of my father's brothers have this problem, and so do my male cousins.

Such a family-clustered problem can only be caused by inherited genes. Yet my three uncles on my father's side are all over 85 and still alive and well, physically strong, some still farming in the countryside. My father is also nearly eighty and can still lift stones weighing over fifty kilograms. Only my third uncle died of colorectal cancer; but when his was discovered he was already 75, and he died at 77—a lifespan close to China's average life expectancy, which was 79 years in 2025.

This shows that although our family's genes make our lives a bit harder, they do not affect our lifespan; my father's side can even be called a long-lived family. When we have diarrhea, taking Bifidobacterium improves it markedly, and without medication it self-resolves within days. This hereditary bowel problem may be related to a familial susceptibility of the gut microbiota and a weaker intestinal barrier; we can rule out ulcerative colitis and Crohn's disease, since the latter are almost unheard of in long-lived families.

Reflecting on my lifestyle over the years, I like a life of both farming and study; I grow not only vegetables but many flowers and plants, so my activity level is much higher than average, though less than my father's generation. I also rarely eat out, eat nothing recklessly at home, and live very self-disciplinedly, so now I go years without diarrhea. I even suspect that the high self-discipline our family inherits is related to our enteritis genes—without self-discipline we could not live normally.

Because I know how to avoid triggers, although I inherited this gene I rarely fall ill; after thirty, the condition has been even more stable. My father's brothers basically stayed home all their lives; only my third uncle was a bricklayer who often worked away on projects when young, eating out frequently, so his gut was repeatedly irritated and inflamed—perhaps one reason he developed colorectal cancer.

But it is not only people with this gene who get colorectal cancer; human genetic differences are tiny, less than one in a thousand between any two people. An unhealthy lifestyle can likewise trigger the disease, and its effect may be even greater; genes merely raise the probability.

Once I chatted with a Beijing colleague who specializes in colorectal cancer. He said their department did a study: a certain research institute near their hospital had more than 2,000 staff, and 15 of them came to their hospital for colorectal cancer treatment within the last five years. The incidence surprised me.

This is related to researchers' lifestyle. As everyone knows, research results are mostly produced by sitting on a cold bench, and such a sedentary life is very bad for gut health. So people in research get anorectal diseases especially often.

This week I took my son to Beijing People's Hospital for his anorectal condition. I spoke with his attending physician, asking what had triggered my son's problem and how to reduce the recurrence rate.

He told me that cases like my son's are extremely common among the universities and research institutes around People's Hospital. Around the hospital are densely clustered many 985, 211, and Double First-Class universities; their teachers and students are basically top scorers above 600 on the provincial gaokao, and they study very hard.

People's Hospital is the designated medical-insurance hospital for these schools and institutes, and this gastrointestinal surgeon has more patients every day than he can handle. Their anorectal diseases are basically caused by sitting; he thinks this group can hardly change their lifestyle now.

The accounts of these two clinicians who deal most with anorectal disease made me realize that, in certain groups—such as universities and research institutes—the incidence of ordinary bowel disease and colorectal cancer is significantly elevated. This is no longer purely genetic; it is mainly caused by lifestyle.

Genes rarely act alone; they always trigger disease together with lifestyle. If you inherit an unfavorable gene but avoid an unhealthy lifestyle, your incidence will still be low, and you may never fall ill.

In our medical genetics class, the teacher emphasized that basically everyone inherits at least four or five susceptibility genes, which predispose people to all kinds of diseases.

With advances in molecular biology and human genetic engineering, one day we may be able to use genetic testing to identify each person's susceptibility genes. Such a report could advise us on how to avoid stacking other risk factors and thereby avoid various familial diseases.

We can also analyze the diseases prevalent among our family members to judge whether we carry certain susceptibility genes, and then design more scientific, targeted plans to avoid them.

People love taking all sorts of psychological tests to judge which profession suits them. In my view, we should also pay attention to how our inherited genes should influence our choice of lifelong career.

For example, if we carry genes that predispose us to colorectal cancer but choose a job requiring long hours of sitting, we have two high-risk carcinogenic factors. If we also love meat and dislike vegetables and fruit, we add another. Each additional high-risk factor greatly raises the probability of colorectal cancer.

Or take someone with a lung-cancer genetic predisposition who likes smoking; they then have two high-risk factors for lung cancer. If they also work in a job involving long-term exposure to dust or asbestos, or live in a heavily air-polluted area, their lung-cancer risk rises further.

Of course, it is not only genes that work this way; other risk factors do too. For example, for a hepatitis B carrier, the hepatitis B virus itself is a high-risk factor for liver cancer and cirrhosis. If they choose a job that requires frequent drinking, they add another. If they also love staying up late and burning the candle at both ends, they add yet another. Several high-risk factors stacking up greatly raise the probability of liver cancer and lower the age at which it appears.

Every wrong choice we make about health will one day exact a terrible price. I have seen many people carefree before falling ill; that is only because they have not yet tasted the agony of disease. Once they are ill, their usual reaction is bitter regret. Better to make the right choices from the start than to regret them on that day.