6. The Mind Changes Matter : Classical Genetics and Epigenetics

There is a saying that what I eat lasts for three generations. Is that really the case?

There is an old saying: “What we eat affects three generations.” Could this truly be the case?

Every living organism on Earth carries its own unique DNA, the fundamental unit of heredity. These genes contain immense amounts of information necessary for forming and sustaining life, and they are passed down from parent to offspring.

In the past, classical genetics taught us that disease was determined primarily by inherited genes. If a certain illness ran in the family, we believed our chances of developing the same disease were high. However, in recent years, a new field of genetics—epigenetics—has shown us that genes are not absolute destiny. While DNA itself does not change, whether specific genes are turned on or off can depend heavily on factors such as environment, diet, and even mental state. This discovery marks a profound shift in how we understand heredity and health.

Take identical twins, for instance. Though they share the exact same genetic code, one may develop diabetes later in life while the other does not. The determining factor? Differences in environment, lifestyle, and stress over the years. This means that even with the same genetic predisposition, the actual outcome depends on how we live.

Ancient wisdom echoes this understanding. The well-known story of Mengzi’s (Mencius’) mother moving house three times to ensure a proper environment for her son shows just how vital surroundings can be. Similarly, the words of Lady Chŏng, mother of the renowned Korean scholar Chŏng Mongju, advising him not to visit Yi Seong-gye’s house because “A white heron should not flock with crows,” reflect an age-old recognition that environment shapes character—and health.

Genes may be fixed, but how they manifest depends on environment, habits, stress, and ultimately, the mind.

Interestingly, the English word for disease—“disease”—literally breaks down into “dis-ease,” or the absence of ease. This suggests not just physical discomfort, but also a lack of mental ease. The common expression “Take it easy” speaks to the importance of emotional calmness.

Parental habits and states of mind are passed down to children not just through words, but through behavior and presence. I wholeheartedly believe—and have seen repeatedly in my clinical practice—that most illnesses begin in the mind. Rather than worrying that our family history dooms us to illness, or blaming others for our condition, we can choose to believe something far more empowering:
Our health is shaped by our own choices, and what we create in our bodies and minds will be passed on to the next generation.

Genes, environment, and thought—matter and mind—are all intricately connected. Even genetics now acknowledges the power of the mind to influence the body.

Dr. Jin-man Kim, director of Peace Oriental Clinic