Epigenetics: Could Your Body Carry Echoes of the Past?

Imagine two babies who inherit similar genes but develop in very different environments. One grows inside a mother who is well nourished and metabolically healthy. The other develops in an environment affected by nutritional deficiency, metabolic dysfunction, stress or other physiological challenges.

Their DNA sequences may be very similar, but will those genes be used in exactly the same way? Perhaps not. And this is where the fascinating science of epigenetics begins.

What is epigenetics?

Think of your DNA as an enormous instruction manual. The words printed in the manual are your genes, but not every instruction needs to be read at the same time.

Epigenetic mechanisms act a little like bookmarks, highlighters and sticky notes placed throughout that manual. They can influence which instructions are given greater attention and which remain relatively quiet, without actually changing the words printed on the page.

One of these mechanisms is DNA methylation, where chemical marks can influence gene activity without altering the underlying DNA sequence. What makes epigenetics particularly fascinating is that our environment can influence some of these processes. Nutrition, for example, is one of the environmental signals our biology responds to.

In other words, the DNA sequence itself does not necessarily need to change for the way our biological instructions are used to change.

The environment can leave a biological fingerprint

One of the most fascinating human examples comes from the Dutch Hunger Winter of 1944–45. During the final months of the Second World War, parts of the Netherlands experienced severe famine.

Decades later, researchers studied people who had been exposed to that famine around the time of conception. Approximately 60 years later, differences could still be detected in DNA methylation at IGF2, a gene involved in human growth and development.

The famine had ended decades earlier and the food environment had changed completely, yet a biological signature associated with that early exposure could still be detected.

This does not mean the famine permanently rewrote their DNA, nor does it prove that the same epigenetic mark was passed unchanged through multiple generations. What it does demonstrate is something remarkable: the environment during the earliest stages of our development can leave biological effects that may still be detectable many decades later.

Why epigenetics matters for South Asians

This becomes particularly interesting when we think about South Asian metabolic health. We know that South Asians tend to develop insulin resistance and type 2 diabetes at younger ages and lower BMIs than many white European populations. We also tend, on average, to have lower lean mass and a higher proportion of body fat at the same BMI.

As I explored in my article on South Asians and diabetes, some of these differences in body composition may have very deep historical roots. But our ancient biology is only one part of the story. The environment in which each new generation develops matters too, and that influence can begin before birth.

Professor Chittaranjan Yajnik and his colleagues provided an intriguing insight into this through their research on Indian babies. Compared with white European babies, the Indian babies tended to be smaller and lighter, but their body composition was not simply a smaller version of the same pattern. Measurements reflecting muscle and abdominal organ size were reduced, while subcutaneous fat was relatively preserved.

Professor Yajnik famously described this as the “thin-fat” Indian baby: a smaller body with less lean tissue, yet relatively preserved body fat.

This suggests that some of the metabolic differences we see in adulthood may have roots much earlier in life. Maternal nutrition and metabolic health, fetal growth, childhood nutrition, physical activity, infections and other environmental influences can all contribute to the way the body develops.

Epigenetics may be one of the mechanisms through which environment and biology interact during these critical stages of life.

Development matters — but it isn’t destiny

The broader concept is often called developmental programming. It describes how the environment experienced during fetal life and early childhood can influence growth, body composition and metabolic health later in life.

A developing baby is constantly receiving information through nutrients, hormones, the placenta and the mother’s metabolic environment. These signals can influence how tissues and organs develop and may affect processes involved in growth, glucose regulation and energy storage.

This does not mean a baby is somehow “predicting” the future, nor does it mean that there is one epigenetic switch responsible for diabetes. Human metabolism is far more complicated than that.

It simply means that development is responsive to the environment, and epigenetic mechanisms are one part of that extraordinarily complex interaction.

This distinction is particularly important when we talk about inheritance. Epigenetics is sometimes presented as though an experience in one generation is automatically written into the biology of children, grandchildren and great-grandchildren. The evidence in humans is much more nuanced.

The nutritional and metabolic health of a mother can directly affect the environment in which her baby develops. That child then grows up within her own nutritional, social and metabolic environment. If she later becomes pregnant, her health becomes part of the developmental environment of the next generation.

That creates a genuine biological connection across generations, but it is not the same as proving that a particular epigenetic mark has been passed unchanged from grandmother to granddaughter.

From grandmother to mother to daughter

Imagine a grandmother who grew up in an environment where nutrition was poor. Her own development may have been influenced by that environment. Years later, when she becomes pregnant, her daughter develops within her particular nutritional and metabolic environment.

That daughter may then grow up in a very different world. Food may be more abundant. Physical activity may decline. Ultra-processed foods may become part of everyday life. Years later, if she becomes pregnant herself, her metabolic health contributes to the developmental environment of her daughter.

Three generations are connected, not necessarily by one mysterious inherited switch, but through a continuing interaction between biology, nutrition, development and environment.

And this is where the story becomes particularly relevant for South Asians today.

When biology meets the modern environment

Within only a few generations, the environment of many South Asian families has changed dramatically. People have moved from villages to cities, while millions of others have migrated to countries such as Britain, Australia, Canada and the United States.

For many, physical labour has declined and cars have replaced walking. Food has become more abundant, while refined carbohydrates and ultra-processed foods are widely available. Eating opportunities have increased, and many of us now spend much of the day sitting.

The environment has changed extraordinarily quickly. Our biology has not changed at the same speed.

This can create what we might call a metabolic mismatch. Someone may have relatively low muscle mass, a lower capacity to safely store excess fat and a metabolic system influenced by fetal and childhood development. That same person then enters a modern environment of energy-dense food, frequent eating and very little stimulus to build or maintain muscle.

This combination may be one piece of the puzzle explaining why some South Asians develop insulin resistance and type 2 diabetes at relatively low BMIs.

It is not because of one gene, one historical event or one particular food. It is the interaction of many biological, developmental and environmental influences. Epigenetics may be one part of that interaction, but it is not the whole explanation.

Could our bodies really carry echoes of the past?

Perhaps — but we need to be careful about what we mean by that.

Our bodies do not literally “remember” the lives of distant ancestors in the way a computer stores a file. Nor can we say that hardship experienced generations ago directly caused diabetes in someone living today.

What we can say is that nutrition and environment can influence development, development can influence later metabolic health, and some biological effects of early-life exposures can persist for decades. We also know that the health of one generation can influence the developmental environment of the next.

That is already an extraordinary story. We don’t need to make it more dramatic than the science allows.

The hopeful side of epigenetics

When people first hear about genetics and epigenetics, it can sound frightening. If my biology was influenced before I was even born, what can I possibly do about it?

But there is another way to look at this.

If the environment matters, then the environment we create today matters too.

The food we eat, the muscle we build, how much we move, how well we sleep and how we manage stress all contribute to the environment in which our metabolism operates. For women who may become mothers, metabolic health before and during pregnancy may also influence the developmental environment of the next generation.

This does not mean that every health outcome is within our control. It means that our biology is responsive, and that creates opportunity.

We cannot change our ancestry or rewrite our early development. But we can prioritise nourishing whole foods and adequate protein. We can build and preserve muscle, reduce our reliance on ultra-processed foods, move regularly, prioritise sleep and look after our metabolic health.

And perhaps that is the most hopeful message of epigenetics.

We may carry biological echoes of the environments that came before us, but we are also helping to shape the environment that comes next.

We cannot rewrite the lives of our ancestors.

But we can influence how the story continues.