The grandchildren of women who were pregnant during the siege — grandchildren who never experienced such violence themselves — nonetheless bear marks of it in their genomes. Passed down through their mothers, this genetic imprint offers the first human evidence of a phenomenon previously documented only in animals: The genetic transmission of stress across multiple generations.

The idea that trauma and violence can have repercussions into future generations should help people be more empathetic, help policymakers pay more attention to the problem of violence, said Connie Mulligan, Ph.D., a professor of Anthropology and the Genetics Institute at the University of Florida and senior author of the new study. 

While our genes are not changed by life experiences, they can be tuned through a system known as epigenetics. In response to stress or other events, our cells can add small chemical flags to genes that may quiet them down or alter their behavior. These changes may help us adapt to stressful environments, although the effects aren’t well understood.

It is these tell-tale chemical flags that Mulligan and her team were looking for in the genes of Syrian families. While lab experiments have shown that animals can pass along epigenetic signatures of stress to future generations, proving the same in people has been nearly impossible. 

Back in Florida, Mulligan’s lab scanned the DNA for epigenetic modifications and looked for any relationship with the families’ experience of violence.

In the grandchildren of Hama survivors, the researchers discovered 14 areas in the genome that had been modified in response to the violence their grandmothers experienced. These 14 modifications demonstrate that stress-induced epigenetic changes may indeed appear in future generations, just as they can in animals

The study also uncovered 21 epigenetic sites in the genomes of people who had directly experienced violence in Syria. In a third finding, the researchers reported that people exposed to violence while in their mothers’ wombs showed evidence of accelerated epigenetic aging, a type of biological aging that may be associated with susceptibility to age-related diseases. 

It’s not clear what, if any, effect these epigenetic changes have in the lives of people carrying them inside their genomes. But some studies have found a link between stress-induced epigenetic changes and diseases like diabetes. One famous study of Dutch survivors of famine during World War II suggested that their offspring carried epigenetic changes that increased their odds of being overweight later in life.

Source: https://news.ufl.edu/2025/02/syrian-violence-epigenetics/