Trauma’s epigenetic impact can span generations

I am a daughter of a Palestinian refugee, violently displaced in 1948 by the precursor militias to the Israeli army. My mother is Syrian from Hama. Trauma is in my family, or should I say, in my DNA. I am also a scientist who studies the genetics and epigenetics of ethnic populations who have been exposed to violence and trauma.

Trauma is portrayed as one event, when for me it is a continuous experience for the past 75 years. People exposed to trauma are usually depicted as in need of saving. Throughout evolution, humans have been exposed to trauma, yet have survived, thrived, and flourished. There may be a different way of understanding the impact of trauma, and I wanted to challenge the existing assumptions.

Epigenetics is an emerging field of research that studies the impact of the environment on our genes.  While the human genome doesn’t change throughout our lifetimes, some life experiences may change how our genes are expressed, which can help us adapt better in different environments.

I wanted to understand how trauma impacts our genes, not only within our lifetimes, but whether it is transferred across generations. I focused on epigenetic changes, which do not alter the DNA sequence, but do change the way genes are expressed.

This kind of research is usually done in animal models. However, the history of dictatorship in Syria has provided the circumstances to search for an intergenerational epigenetic signature of trauma in humans.

Because of my familiarity with Syrian history, we examined how trauma exposure impacts gene expression during different life stages. We compared three groups, families where the grandmother experienced trauma during pregnancy in the 1982 massacre, families where the mother experienced trauma during pregnancy in the 2011 civil uprising, and a control group of families who fled to Jordan before the 1982 massacre and thus had no direct trauma exposure during pregnancy.

The research is a case study of community collaboration and partnerships. It was not easy to find the families who fit the specific criteria and agreed to share their data. I collaborated with Dima Hamdmad, a Syrian researcher with whom I worked over a period of 10 years in engaging the Syrian communities, building trust and agency. As families understood our research purpose, they agreed to participate, knowing that scientists from their community with similar experiences would carry out the work to understand how trauma can impact them and their offspring. We collected data and cheek swabs from the families.

I needed an expert to identify the trauma and other environmental exposures. So, I reached out to Catherine Panter-Brick, a professor of medical anthropologist from Yale University, who works with refugees. Panter-Brick supervised and funded the identification of trauma exposure and other environmental exposures in the study.

As a professor at Hashemite University in Jordan, a developing country, I did not have funding or lab resources to conduct the epigenetics analysis, so I invited Connie Mulligan, a professor of genetics at the University of Florida, to be a partner in the study to fund and conduct the epigenetic analysis.  The sophisticated statistical analysis was performed by Mulligan, her lab, and Alexandra Binder, from the University of Hawaii. The results were a truly collaborative discovery that would not have been possible without every partner contributing.

We analysed 850,000 sites in the genome where DNA methylation — an epigenetic change that regulates how genes are turned on or off — takes place. DNA methylation is the most common type of epigenetic modification. It doesn’t alter the DNA sequence itself, but it can significantly influence how genes function.

We identified 21 sites where methylation was linked to individuals who experienced violence directly, and 14 sites associated with inherited exposure to trauma from earlier generations. This is the first time such intergenerational epigenetic signatures were shown to be present in third generations of humans who were not exposed to the violence themselves. Normally, these kinds of epigenetic methylation marks are erased before birth in a process known as epigenetic reprogramming, which resets gene expression for the next generation. However, our findings suggest that some of these marks may evade reprogramming.

This indicates that certain gene expression changes caused by traumatic experiences can be passed from one generation to the next. We propose that these inherited epigenetic changes may help future generations adapt to difficult environments, including exposure to violence and psychosocial stress.

We were able to show for the first time that exposure to violence during pregnancy can speed up epigenetic ageing, highlighting pregnancy as a crucial developmental period. This is more important than ever because of the number of pregnant women in Gaza today exposed to what the UN Special Committee, Amnesty International and others have named as an ongoing genocide.

The results impact our understanding of evolution and how traumatic experiences can be transferred across generations.  Even though our study focused on refugees, our results are relevant to all populations and different types of violence.

Another unique aspect of our research is its cross-disciplinary approach. The study was initiated by a scientist from the Middle East and global south and a descendant of refugees. This challenges the stereotype in which scientists in the West come up with an idea and search for a partner from the global south to help in data collection. Our case here is different, reversed, and collaborative, which is necessary to understand the complexity of human nature and the underlying biological mechanisms so that we may create a better world for future generations.

Our findings suggest an alternative narrative to the Western victim-based framing of trauma. Epigenetic signatures of trauma may serve higher regulatory functions, offering future generations a spectrum of adaptive strategies for unpredictable environments, much like other intelligent and social organisms such as the octopus.

I call this ‘my grandmother’s wisdom’. Recognizing this resilience shifts how we approach policy, interventions, and scientific inquiry. Shifting from victimhood and vulnerability to agency and adaptability.

This perspective calls for celebrating diversity, trusting communities to shape their own futures, and embracing a decolonized approach to science—one that serves humanity by fostering understanding, resilience, and equity.

I visited one of the Syrian families after the publication of the study to share the results. I had visited the family 10 years ago when we first collected the samples. The family could finally talk freely about what they had endured and were full of hope on the implications of the research in bearing witness and holding the fallen Assad regime accountable. The granddaughter, who was 2 in 2015 is now 12, and aims to be a physician.

We plan to explore further steps to understand the functions of the different sites we had discovered: whether they are connected to health and behaviour; what the transfer mechanism is; and whether our findings are replicable. We plan to explore transgenerational epigenetic signature of trauma in four generations of Palestinian families.

I have a granddaughter of my own, and the experience has changed me, realizing the responsibility we hold to create a better future for future generations.

The original research article, published in Scientific Reports, is here.

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