Grandma's Experiences Leave a Mark on Your Genes

Your ancestors' difficult childhoods or thrilling adventures might shape who you are today.

These experiences can influence how genes in the brain are expressed, possibly passing on traits like anxiety or resilience by changing their epigenetic patterns.

Darwin and Freud walk into a bar. Two mice – a mother and her son – sit on stools, sipping gin from tiny thimbles.

The mother mouse looks up and asks, “Hey, geniuses, can you tell me why my son ended up like this?”

“Blame bad genes,” says Darwin.

“Blame bad parenting,” says Freud.

For over a century, those two views – nature vs. nurture, biology vs. psychology – offered competing answers to how behavior forms and why it continues not only in one person, but across generations.

In 1992, two young scientists, inspired by Darwin and Freud, walked into a bar. After a few beers and a lively conversation, they began to build a new theory that explained how life experiences could directly affect your genes, not just your experiences but those of your mother, grandmother, and even earlier generations.

The bar was in Madrid, where Spain’s oldest neuroscience research center, the Cajal Institute, hosted an international conference. Moshe Szyf, a molecular biologist and geneticist from McGill University in Montreal, had never studied psychology or neuroscience. However, a colleague convinced him to attend, thinking his research could be useful in those fields.

The same colleague persuaded Michael Meaney, a neurobiologist also at McGill, to attend. The idea was that Szyf’s expertise might offer new insights into Meaney’s work with animal models related to maternal neglect.

“I can still picture it – a little corner bar that served pizza,” Meaney recalls. “Moshe keeps kosher, so he was focused on finding kosher-friendly calories. Beer fits the bill. He can have beer anywhere. And I’m Irish, so beer works for me too. It was a great match.”

The two quickly got into a lively discussion about a new and exciting area in genetics. Since the 1970s, scientists have understood that the coiled DNA strands inside each cell’s nucleus need additional instructions to determine which genes should be activated, whether the cell is meant to become part of the heart, liver, or brain.

One of those extra elements is the methyl group, a common part of organic molecules. Methyl groups act like bookmarks in a cookbook. They attach to DNA inside each cell and help pick out only the specific "recipes" – or genes – needed to make that cell’s proteins. Since these groups sit on the outside of genes without changing the DNA sequence, the study of these changes became known as epigenetics. The term comes from the Greek word epi, meaning over or above.

At first, scientists thought epigenetic changes happened only in the womb. But breakthrough research revealed that these molecular tags could be added to DNA even in adulthood, leading to major changes in how cells behave, including cancer. In some cases, these methyl groups were added due to diet. In others, exposure to certain chemicals was responsible. Szyf showed that it was possible to reverse these changes with medication, and in doing so, cure some cancers in lab animals.

What truly surprised researchers was the discovery that epigenetic changes could be inherited. A study by Randy Jirtle at Duke University showed that when mother mice were given diets high in methyl groups, their offspring had permanent changes in fur color. This happened without any changes to the actual DNA. Like a genetic mutation, these methyl markers could be passed down through generations.

Back at the bar in Madrid, Szyf and Meaney started thinking about a question that seemed unlikely but deeply important: If diet and exposure to chemicals can change how genes work through epigenetics, could life experiences – like childhood neglect, drug addiction, or extreme stress – also cause similar changes in the DNA inside brain cells? That idea became the foundation of a whole new area of study called behavioral epigenetics. This field is thriving today, with many research projects and potential breakthroughs in treating mental health and brain disorders.

Behavioral epigenetics has led to a powerful understanding: traumatic events in our lives – or even those in our family’s past – can leave lasting marks on our DNA. These are not changes to the DNA sequence itself, but chemical tags that stick to it. People whose ancestors faced extreme hardship – Jews whose great-grandparents fled violence in Russian shtetls, Chinese families affected by the Cultural Revolution, African immigrants whose parents lived through genocide, or individuals of any background raised by abusive or alcoholic parents – carry more than painful memories. They may also carry biological traces of those traumas.

Just like silt left behind on the gears of a delicate machine after a tsunami, our experiences – and those of our ancestors – don’t simply vanish. Even if they fade from memory, they stay with us as a molecular imprint on our genetic framework. The DNA itself doesn’t change, but emotional and behavioral patterns can be passed down. You may have inherited not just your grandmother’s bony knees, but also her tendency toward depression, shaped by the neglect she faced as a baby.

Or maybe not. If loving caregivers adopted your grandmother, you might benefit from the positive influence of their care. Behavioral epigenetics doesn’t only explain inherited struggles – it also helps us understand how resilience and strength can be passed down. And if your family history includes trauma or emotional distance, new drug treatments might one day reverse not just your mood, but the actual epigenetic shifts linked to those experiences.

Think of it like an old dress passed down through generations. You can wear it as is or have it altered to fit you better. While the genome is still considered life’s blueprint, the epigenome is more like an Etch A Sketch – shake it hard enough, and it may be possible to erase the marks of the past.