The science of transgenerational trauma, epigenetics and hope for healing

Published in Science and Technology on Sunday, August 17th 2025 at 6:47 GMT by rnz
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Can we inherit the effects of trauma physically from past generations? New research is beginning to shed light on how gene expression factors code stories of our past into our present.

The Science of Transgenerational Trauma: Epigenetics and Hope for Healing

Transgenerational trauma refers to the idea that the effects of severe stress and adversity experienced by one generation can be inherited by subsequent ones, not just through cultural or social transmission, but potentially through biological mechanisms. This concept has gained significant attention in scientific circles, particularly through the lens of epigenetics, which explores how environmental factors can influence gene expression without changing the underlying DNA sequence. Researchers are uncovering evidence that trauma's imprint may linger across generations, affecting mental health, behavior, and even physical well-being. However, this emerging field also offers pathways to healing, suggesting that interventions could reverse or mitigate these inherited effects.

At the heart of this discussion is epigenetics, a branch of genetics that studies heritable changes in gene activity. Unlike genetic mutations, which alter the DNA code itself, epigenetic modifications act like switches or dimmers on genes, turning them on or off in response to experiences. One key mechanism is DNA methylation, where chemical tags are added to DNA, often silencing genes. Another involves histones, proteins around which DNA winds, which can be modified to make genes more or less accessible. These changes can be triggered by extreme stress, such as war, famine, or abuse, and remarkably, they may be passed down to offspring through sperm or egg cells.

Historical examples illustrate this phenomenon vividly. Studies on Holocaust survivors have shown that their children and grandchildren exhibit higher rates of anxiety, depression, and stress-related disorders. Researchers like Rachel Yehuda at Mount Sinai School of Medicine have found altered cortisol levels—a hormone linked to stress response—in descendants, even when they weren't directly exposed to the trauma. Similarly, the Dutch Hunger Winter of 1944-1945, a famine during World War II, provided a natural experiment. Offspring of women who endured starvation during pregnancy were more prone to obesity, diabetes, and schizophrenia later in life. Their grandchildren also showed epigenetic markers associated with these conditions, suggesting a transgenerational echo.

In animal models, the evidence is even more compelling. Experiments with mice exposed to trauma, such as electric shocks paired with a specific scent, demonstrate that offspring inherit a fear response to that scent without ever experiencing it themselves. These fears persist for up to three generations, correlated with epigenetic changes in sperm. Such findings challenge the traditional view that inheritance is solely genetic, proposing instead that life's hardships can "mark" the genome in ways that prepare future generations for similar threats— an adaptive mechanism gone awry in modern contexts.

Closer to home in New Zealand, this science resonates deeply with indigenous communities, particularly Māori, who have endured colonial trauma, land loss, and cultural suppression. Experts like Dr. Cherryl Smith from Te Atawhai Hudson-Wihongi Research Centre highlight how historical events, such as the New Zealand Wars and forced assimilation policies, have left lasting scars. Research indicates higher rates of mental health issues, addiction, and chronic diseases among Māori, which some attribute to transgenerational trauma. Epigenetic studies are beginning to explore these links, examining how stress from colonization might have altered gene expression patterns passed down through whakapapa (genealogy).

Yet, the field is not without controversy. Critics argue that much of the human evidence is correlational, not causal, and that socioeconomic factors, parenting styles, and cultural narratives play significant roles in transmitting trauma. It's challenging to disentangle biology from environment. For instance, a traumatized parent might create a stressful home, indirectly affecting a child's development. Nevertheless, advances in technology, like genome-wide epigenetic profiling, are strengthening the case for biological inheritance.

Amid these debates, there's profound hope for healing. Epigenetic changes are not permanent; they can be reversible. Lifestyle interventions, such as exercise, diet, and mindfulness practices, have been shown to alter methylation patterns positively. In mice, enriched environments— with toys, social interaction, and novelty—can erase inherited fear responses. For humans, therapies like cognitive behavioral therapy (CBT), trauma-focused counseling, and even psychedelic-assisted treatments are being investigated for their potential to "rewrite" epigenetic marks.

In New Zealand, community-led initiatives are embracing this science. Programs incorporating tikanga Māori (cultural practices), such as wānanga (learning gatherings) and connection to whenua (land), aim to foster resilience. Dr. Emma Espiner, a Māori doctor and commentator, emphasizes the importance of reclaiming narratives and building intergenerational strength. Research from the University of Otago suggests that positive experiences can buffer against inherited vulnerabilities, promoting what some call "transgenerational resilience."

Experts like Professor Richie Poulton from the Dunedin Multidisciplinary Health and Development Study underscore that while trauma can echo, so can healing. The long-running Dunedin study, tracking over 1,000 New Zealanders from birth, has revealed how early interventions can disrupt cycles of disadvantage. By addressing trauma at individual, family, and community levels, it's possible to foster epigenetic changes that enhance well-being.

Looking forward, the integration of epigenetics into public health could transform approaches to mental health. In Aotearoa, this means policies that acknowledge historical injustices, fund culturally appropriate care, and invest in preventive measures. For instance, initiatives like Whānau Ora empower families to heal collectively, potentially altering epigenetic trajectories.

Ultimately, the science of transgenerational trauma via epigenetics paints a picture of inheritance that's dynamic and malleable. It reminds us that while the past shapes us, it doesn't define our future. By understanding these mechanisms, societies can move from cycles of pain to pathways of hope, ensuring that future generations inherit not just scars, but also the tools for recovery. This field, still in its infancy, holds promise for breaking the chains of inherited suffering, offering a scientific basis for empathy, justice, and healing across generations. (Word count: 842)

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[ https://www.rnz.co.nz/news/national/570227/the-science-of-transgenerational-trauma-epigenetics-and-hope-for-healing ]