As war continues to rage in Gaza and Ukraine, there is concern about how the related trauma might be transmitted to future generations of people in those regions.

More generally, interest in the idea of transgenerational trauma has recently surged. For example, earlier this year, National Geographic magazine asked whether genes carry past family trauma.

But while this might be a catchy question, it’s also slightly misleading. Because while trauma can ripple across generations, shaped by how our bodies respond to their environments, its effects aren’t hard-coded in our genes.

Plastic minds and bodies

At the heart of this process is what’s known as phenotypic plasticity.

This is the capacity for organisms to produce different outcomes from the same genes, depending on their environment. These outcomes, called phenotypes, can include stress sensitivity and body shape.

One way different phenotypes can arise from the same genes is via epigenetics: small chemical changes to the DNA molecule that make particular genes more or less active. Think of these like a director’s notes on a script. These notes guide the cell on which lines to emphasise or soften, without changing the script itself.

But epigenetics is just one way this plasticity is expressed.

Understanding how trauma is passed across generations means looking beyond genes and cells to the environments that shape and influence them.

Human development is sculpted by lived experience, from caregiving and community to stress, safety and belonging.

These factors interact to produce lasting – but not always fixed – effects. By focusing on how they interact, rather than on single causes, we can better understand why trauma echoes across generations. This also helps us identify how that cycle might be disrupted.

Widespread in nature

Phenotypic plasticity is widespread in nature.

In honeybees, genetically identical larvae become queens or workers depending on what they eat while developing. In three-spined stickleback fish, early exposure to predators reshapes their stress physiology and body shape, making them harder for predators to grasp.

These aren’t genetic differences – they’re environmental effects on development.

In humans, early-life conditions similarly shape development. A child raised in an unsafe setting may develop heightened vigilance or stress sensitivity – traits that help in danger but can persist as anxiety or chronic stress in times of safety. This is known as environmental mismatch.

Across generations, plasticity becomes more complicated. In some of my past research, I studied how diet in one generation of fruit flies shaped health, reproduction and longevity in their offspring and grand offspring.

The results varied depending on diet, generation and trait. Traits that appeared to be useful in one generation weren’t always so in the next. This highlights how difficult transgenerational effects are to predict – precisely because of this plasticity.

Too narrow an explanation

Epigenetics often reflect environmental exposures – such as stress, trauma, nutrition or caregiving. But they’re not necessarily permanent “scars”. Many are dynamic and can shift with changing environments – especially early in life.

Studies show that epigenetic patterns linked to early childhood adversity vary depending on later environments such as family stability and social support. This suggests the biological imprint of early stress is shaped by what happens next.

It’s tempting to treat epigenetics as the key to explaining inherited trauma – but that’s too narrow. Trauma can influence the next generation through altered hormones, immune function or in utero conditions – all of which shape brain development and stress reactivity.

Genetic variation also plays a major role. It doesn’t encode trauma itself, but it shapes traits such as sensitivity to threat or emotional regulation. These traits aren’t chosen – they arise from a web of biological and social influences beyond our control.

But how they unfold, and whether they’re amplified or softened, depends on the systems that surround us.

Connection to culture

Connection to culture plays an important role too.

In Aotearoa New Zealand, Māori-led initiatives that centre land, language and whakapapa (ancestral lineage) have shown promise in restoring wellbeing after generations of colonisation-related trauma.

For Holocaust survivors and descendants, connection to cultural identity through ritual and shared narrative can reduce the psychological burden of transmitted trauma.

But not all trauma is collective or institutional. Interventions such as trauma-informed parenting and early relational therapies have been shown to improve outcomes in the next generation.

These psychological supports affect biology. Feeling safe in our relationships, having stable routines and a sense of meaning can reduce stress hormones, modulate immune function, and buffer against long-term disease risk.

In this way, culture, caregiving and connection are all biological interventions. When they soften the effects of earlier stress, they may help interrupt its transmission.

Reframing inherited vulnerability

This matters, because it changes how we understand inherited vulnerability.

Rather than a permanent wound passed down through DNA, the effects of trauma are better understood as changeable responses shaped by context.

Thanks to plasticity, our biology is always in conversation with the environment – and when we change the context, we can change the outcome.