We pass down our eye color and baldness to our kids. It seems we also pass along health problems from bad food we consume and smoke we inhale.

A fast food burger against the backdrop of DNA strands

Two hands hold a fast food burger against the backgrop of DNA strands. Illustration by News Decoder

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Is our children’s health predestined before they take their first breath?

It turns out the answer is yes: We don’t just pass on our DNA to our children, but also the molecules that are influenced by our experiences — the good, the bad and the ugly.

The genes we inherit from our parents, our DNA, serve as the blueprint for our development. We pass them on to our children, then they to theirs and so forth.

Modern lifestyles have resulted in new experiences and new exposures, such as processed high-fat and high-sugar foods, a stressful environment, less exercise and more exposure to air pollution. These shifts not only affect well-being but have repercussions for the next generation and those that follow.

Teams of scientists worldwide are digging into the effects of our lifestyle habits on the health of our children and the generations to come.

A collaboration between researchers at the University of Southampton in Great Britain and at the University of Bergen in Norway found, for example, a link between fathers who smoke and a higher risk for their children of asthma, low lung function and obesity.

They are what we eat.

The link is something scientists have termed epigenetics: the study of how our behavior and environment can affect how cells in our bodies work.

It has long been established that our experiences can cause changes that affect the way our genes work; our behaviours and environment can leave distinctive signatures on our genes through the phenomenon of epigenetics.

Now, recent studies demonstrate that these experiences may be directly transmitted to offspring.

We understand how a woman’s health throughout pregnancy, childbirth and the postnatal period can affect a baby. A pregnant woman’s actions and environment have a significant influence on the developing embryo and fetus. Later, her choices while breastfeeding can affect what is transmitted to the baby through breast milk.

Until now, the father seemed a bit irrelevant. But emerging data now seems to imply that his lifestyle is important too. It influences offspring in other ways, potentially making them more susceptible to a range of disorders, particularly those affecting the brain.

The saying “like father, like son” now seems to have real biological substance. It turns out health habits shape the destiny of generations to come.

Bad habits imprinted in our molecules

Environmental exposures can alter the epigenome, the collection of molecules found in and around the DNA in human cells, resulting in unique signatures specific to each exposure that persist throughout life.

“The memory of the exposure is being passed through generations,” said John Holloway, a researcher at the University of Southampton who specializes in the genetic and epigenetic regulation of allergy and airways disease.

For instance, smoking can produce three distinct patterns of change in someone’s DNA: one from maternal smoking, another from personal smoking and a third from the father’s smoking before conception. So a person’s risk of developing a disorder is influenced by a combination of inherited genes, personal habits, maternal exposures and the father’s preconception habits.

“It all adds up,” Holloway said.

Historically, the spotlight has been on Darwin’s theory of evolution — that random genetic changes in organisms occur randomly and accumulate over time. This supports the concept of natural selection as some of the genetic changes might make a species more suited to surviving changes in the environment or cataclysmic events.

Our food selections and natural selection

Natural selection can alter a species in small ways, causing changes over several generations, for example the development of shorter fingers and longer opposable thumbs to allow humans to firmly grasp and manipulate objects. It is also capable of creating entirely new species and is responsible for the transformation of dinosaurs into birds and the common ancestor of apes and humans into today’s people, chimpanzees and gorillas.

The theory underscores a gradual process that unfolds over hundreds of years. But it doesn’t explain the immediate effects of the habits that rapidly influence offspring.

Like Darwin, the French biologist Jean-Baptiste Lamarck believed that organisms adapt to their environments and pass on these adaptations.

Lamarck proposed that organisms achieve this by changing their behaviour and, consequently, their bodies — like an athlete working out and getting buff — and that these changes are passed through to offspring.

For instance, Lamarck thought that giraffes originally had shorter necks, but their ancestors stretched their necks to reach tasty leaves just out of reach. This stretching of the neck was inherited by successive generations, he proposed, ultimately resulting in the long necks that giraffes now have.

Lamarck believed that within just one generation, parents can send information to their offspring to increase an adaptation. But is this adaptation always a good thing?

A bad diet can alter sperm.

In a study conducted at The Florey Institute of Neuroscience and Mental Health in Melbourne, Australia, scientists fed mice a modern Western junk-food diet of high-fat high-sugar food. The result? Changes in the males’ sperm that not only altered brain development but also gut development and their offsprings’ microbiomes, the collection of all of the microbes in their bodies.

Anthony Hannan, a brain researcher at The Florey who investigates gene-environment interactions in brain disorders, said that these changes in the mice may also happen in humans. The study suggests that sperm could carry information about the father’s diet, potentially influencing the development of his offspring, he said.

Notably, the cells responsible for forming sperm throughout a man’s life develop during puberty. So what a teen eats and does during this critical period can have a lasting effect on sperm development and the genetic information passed down to subsequent generations.

According to other data, exposures can potentially be passed on to great-grandchildren. Hannan says these factors may contribute to higher occurrences of depression, anxiety disorders and other cognitive issues. The brain appears to be the primary organ affected by this transgenerational epigenetic inheritance, affecting its development, structure and function.

Understanding these connections is crucial for shaping new public health policies and finding ways to prevent diseases down the line, making sure we’re looking out for the health of future generations.

Holloway has this message to teenagers: “The things that you’re exposed to don’t just have a consequence for yourself but could have consequences for your future children.”

questions to consider:

  1. What is epigenetics? 
  2. How can our diets affect our children who aren’t yet born?
  3. What habits do you have that might affect the genes you might pass on to your offspring?

Madison Stringer is a journalist with a background in neuroscience based in Geneva, Switzerland. She writes about brain and health research to bridge the gap between research and health care, disseminating crucial findings to empower health professionals and enhance public well-being. She is currently a fellow in the Dalla Lana Fellowship in Journalism and Health Impact at the University of Toronto. 

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