Recent research suggests that trauma may be hereditary. Is it true that members of younger generations suffer more under the weight of the horrors their ancestors endured than children of non-traumatized parents?
The word “trauma” comes from Greek, where it originally meant “injury” or “wound.” For many centuries, it was used only to refer to physical injury; it was not until the famous revolutionary in psychology, Sigmund Freud, expanded its meaning to the form we know today. At the beginning of the twentieth century, Freud described “trauma” as “an experience that, within a short period of time, overwhelms the mind with a surge of stimulus too intense to be processed or dealt with in the normal way“.
A traumatic event is one in which we perceive a threat of psychological or physical danger. We are terrified, trapped, and helpless. Our brain cannot draw from the catalog of responses used in everyday life, and therefore extreme threat can trigger anything from apathetic “freezing” through dissociation to panic, terror, and uncontrollable behavior.
Exposure to traumatic events (which may include e.g., war, the death of a loved one, a car accident, physical or sexual violence, torture, abuse, bullying, humiliation…) can lead some individuals to develop post-traumatic stress disorder (PTSD) or Complex PTSD: These mental health conditions are characterized by symptoms such as flashbacks of the horrors experienced, impaired concentration, mood swings, increased aggression or withdrawal, and various problems in interpersonal relationships.
However, trauma does not end with devastating effects on the individual—the victim of an unfortunate, merciless situation. Recent research suggests that its consequences may be far-reaching: a traumatized individual does not take their troubles “to the grave,” but rather unconsciously passes them on to their descendants over the course of their life, from whom they are then passed on to subsequent generations, and so on.
Numerous studies point to “a whole range of affective and emotional symptoms passed down from generation to generation,” across a wide variety of populations, “including the descendants of survivors of abuse, armed conflicts, and genocide”. These symptoms include for example distrust of the world, pervasive fearfulness, increased stress, an inability to express emotions or talk about them with others, “chronic sadness,” and others.
Much of the research to date on the intergenerational transmission of trauma has focused on the victims of one of the worst atrocities in history—the Holocaust. According to the following studies, the children of those who survived the horrors of World War II have, for example, a greater tendency to develop PTSD as well as other mental disorders; compared to the “general” population, they are also less able to cope with stress. Henry Krystal, a professor of psychiatry and a Holocaust survivor, in his work identified the so-called “survivor syndrome” (survivor syndrome) – a “cluster” of symptoms consisting of avoidance of social situations, insomnia, nightmares, chronic depression or anxiety, or somatization (physical health problems stemming from psychological distress—e.g., pain, fatigue, digestive issues). According to him, families affected by disasters tend to be “sadomasochistic and emotionally crippled, (…) burdened by guilt and shame, obsessed with the past“.
A a study examining the children of prisoners of war: regardless of socioeconomic status and family relationships, the sons of fathers imprisoned in inhumane conditions died earlier than the children of parents who had not endured these horrors… even though they themselves were not exposed to any danger. The hope for an explanation of this phenomenon lies in epigenetics—the science that examines how the environment, life experiences, and behavior influence gene expression.
Epigenetics researcher Randy L. Jirtle, in interview with The Atlantic noted that in the case of prisoners of war, the effects could have been hereditary consequences of war-related stress, malnutrition, or a combination of both. Environmental factors determine the activation or deactivation of certain genes, which can cause the health problems described above. An example illustrating this is data showing that the average health of residents in states that suffered from food shortages during the American Civil War was poorer.
Another example is a recent study that discoveredthat the children of Holocaust survivors, just like their parents, exhibited an epigenetic change—known as DNA methylation—in a region of the gene that influences stress. The researchers ruled out the possibility that these children had experienced any trauma themselves, and the results therefore point to the heritable transmission of the consequences of traumatic experiences.
The same has been demonstrated in countless animal experiments—ranging from the more dramatic examples of water fleas, which, when exposed to the scent of a predator, gave birth to offspring with armored, spiny heads, to the classic mouse cages full of research opportunities: for example, scientists have discovered that if a generation of parent mice is exposed to a special diet, low temperatures, or toxic substances, the next generation of mice will differ significantly in behavior and weight.
Researcher Isabelle Mansuy is trying to get to the bottom of the intergenerational transmission of trauma by observing the behavior of the offspring of traumatized mouse mothers—the mothers are, for example, isolated from their offspring at various intervals, confined in tubes, and thrown into water… and indeed, epigenetic changes in the mouse pups result in increased stress, depressive behavior, or poorer parenting skills, among other effects… However, particularly noteworthy is a discovery from the same laboratory: traumatized mice raised in a supportive environment did not pass on their distress to subsequent generations via their genetic sequence. “These limited findings (…) suggest that life experiences can be both healing and harmful at the molecular level,” writes A. Curry.
The same conclusion was reached by study, which surveyed the descendants of Holocaust survivors—traumatic experiences can be passed down from generation to generation through communication, but so too are ways of coping with hardship, or increased resilience.
Those who seek will easily find plenty of evidence for the phenomenon of the genetic transmission of trauma from generation to generation. It seems like an almost intuitive idea—it almost prompts a reaction like, “What? Nobody thought of that before?” —after all, if customs and traditions are passed down across generations, why shouldn’t the same be true for darker, life-complicating issues?
In addition to studies confirming the transgenerational transmission of trauma there are at least as many that have found no evidence… and studies presenting evidence “in favor” are often met with well-deserved criticism from other scientists: whether it’s an overreliance on case studies rather than larger-scale research involving more people, unclear definitions, small sample sizes, or the absence of control groups—these are obstacles on the path to knowledge are not few.
It’s still too early to draw conclusions—but this fascinating chapter in psychological research is expanding day by day, quite possibly leading to discoveries that will help many people in the future—because, unfortunately, disasters and traumas aren’t likely to go away anytime soon.
