Shimofuri Myojo’s Soshina Reveals His Fear of Inheriting Diabetes — What Doctors Want You to Know

Hereditary tumors passed down through generations

“I really hate going to the hospital.”

That offhand remark came from Soshina (32), one half of the comedy duo Shimofuri Myojo, during an episode of Shimofuri Myojo’s All Night Nippon. Yet what followed made many listeners uneasy.

“When I sleep, I wake up three or four times to pee. My throat gets insanely dry. My dad had diabetes, so maybe I’m in the prediabetic stage too? That scares me.”

His partner Seiya (33) laughed and said, “You sound like an old man!” But Soshina, though half-joking, seemed somewhat serious. Last year, when he took a break from TV appearances due to health issues — without disclosing details — he said on his YouTube channel, “There’s a tendency for that in my family.”

Feeling anxious that “I might get the same illness as my parents” is not unique to Soshina. But how much do a parent’s medical conditions actually affect their children? Dr. Yu Masumori, a general medicine specialist at Hakodate Ryouhoku Hospital, explains:

“Diseases like cancer, diabetes, and high blood pressure aren’t determined by a single gene. They result from a combination of multiple genetic traits and lifestyle factors such as diet, exercise, and smoking. We call these multifactorial diseases.”

So it’s not as simple as you’ll definitely get it because it runs in the family. However, there are exceptions.

“About 5–10% of all cancers are hereditary tumors. These are caused by specificgenetic mutations that create a predisposition to disease, passed down through generations — what we call hereditary tumors.”

Cancer, heart disease, diabetes, and mental disorders — and their genetic links

So how can we tell when a disease is strongly influenced by genetics?

“To be honest, it’s difficult to clearly separate genetic from environmental causes at the individual level. However, diseases with particularly strong genetic influence tend to show some characteristic signs:

• Onset at a young age (for example, colon cancer in one’s 40s)
• Multiple family members with the same illness
• A person developing cancer in multiple organs
• Distinctive physical traits (phenotypes) associated with the condition

When these features are present, it’s likely a hereditary condition,” explains Dr. Masumori.

For example, yellowish lumps on the Achilles tendon caused by cholesterol buildup—called tendon xanthomas—are an important sign of familial hypercholesterolemia (FH), a genetic disorder in which LDL (bad) cholesterol levels become abnormally high. These physical clues help specialists identify patients who may need urgent medical attention.

TV personality Nicole Fujita (27) drew public attention when she revealed she had familial hypercholesterolemia. For years, health checkups flagged her high cholesterol levels, but she ignored them—until multiple relatives suffered heart attacks. After undergoing testing, she was diagnosed with FH. With medication and lifestyle changes, her levels stabilized and her health risks dropped significantly.

“If left untreated, FH can lead to heart attacks at a young age. But if detected early and managed properly, the outlook changes dramatically. That’s why it’s crucial not to ignore family history or physical warning signs,” says Dr. Masumori.

So what about the major illnesses that most concern Japanese people—cancer, heart disease, diabetes, and mental disorders? Dr. Masumori offers the following explanations:

Cancer

“Most cancers are multifactorial—caused by both genetic and lifestyle factors. However, some hereditary tumors carry a much higher risk. Representative examples include HBOC (Hereditary Breast and Ovarian Cancer Syndrome), which greatly increases the risk of breast and ovarian cancer, and Lynch syndrome, which raises the risk of colorectal and endometrial cancers.

These can be diagnosed through genetic testing, and concrete preventive strategies—such as regular surveillance and even risk-reducing surgery—are well established.”

Heart Disease

“Heart diseases caused by arteriosclerosis—like heart attacks and angina—are mostly multifactorial. But familial hypercholesterolemia (FH) is an exception. Because the body has a congenital inability to properly break down LDL cholesterol, arteriosclerosis progresses rapidly from a young age. The risk of heart attack can be dozens of times higher than in healthy individuals.

Having a relative who suffered a heart attack before age 55 (for men) or 65 (for women)—known as premature coronary artery disease—is a serious warning sign.”

Type 2 Diabetes

“Type 2 diabetes is a classic multifactorial disease. A genetic predisposition to insulin resistance combines with lifestyle factors—overweight, lack of exercise, and poor diet—to trigger the condition. Having a family history of diabetes is itself a significant, independent risk factor.”

Mental Disorders

“In conditions like schizophrenia, a family history increases the likelihood of developing the illness. However, genetics alone never determine it. Environmental influences—such as stress and upbringing—play a major role in whether or not the disease manifests.”

The higher the genetic risk, the greater the impact of prevention

Learning about one’s genetic risks can feel discouraging, but Dr. Masumori stresses that you can lower your risk through your own efforts.

“In fact, the higher your genetic risk, the more powerful the effects of healthy habits become. By following the five key pillars of medical prevention, you can cut your risk of heart disease and diabetes by half.

First and foremost, quit smoking—it’s the single most effective health habit.

Second, make sure to stay physically active in daily life. Start by moving 10 minutes more than you do now, and aim for about 150 minutes of activity per week—for example, a 20-minute brisk walk each day.

Second, make sure to stay physically active in daily life. Start by moving 10 minutes more than you do now, and aim for about 150 minutes of activity per week—for example, a 20-minute brisk walk each day.

Maintaining a healthy body weight is also essential. Obesity is said to be the root of many illnesses. Check your BMI (weight in kg ÷ height in m ÷ height in m) and aim to stay within the normal range.

When it comes to diet, balance is the key. Limit salt and animal fats—especially saturated fats—and eat plenty of vegetables, fruits, and whole grains such as brown rice and whole-wheat bread.”

Soshina’s words — “My dad had diabetes, so it scares me” — resonated with many people. But heredity is not a curse that seals one’s fate.

As Nicole Fujita’s case of familial hypercholesterolemia (FH) shows, knowing your medical history allows you to detect problems early and take steps to change your future. Talking with your family about health history can be the most effective form of prevention.

“You can’t manage a genetic risk you don’t know about. Discuss your family’s medical history with your parents and grandparents, and share that information among family members — that’s the first step in prevention. Keep up with regular checkups, and if something worries you, consult a doctor early,” Dr. Masumori advises.

Rather than fearing genetics, learn, prepare, and take action.
Conversations about your family’s medical past can become the guiding light that protects both you and your loved ones.

Yu Masumori (Masumori Yū)

A general medicine physician working at a community hospital in Sapporo, Hokkaido. Actively shares medical insights through platforms such as YouTube Medical University and Medical Student Dojo Channel, as well as on social media. In 2023, he launched Hakodate Kurashi no Hokenshitsu (“Hakodate Community Health Room”) to strengthen connections between local residents and healthcare professionals. Author of “The Ageless Way of Living After 70: Lessons I Learned from My Patients as a General Practitioner”(KADOKAWA).