Inheritance of trauma

Like mother, like daughter, like granddaughter. Many traits can be inherited, including trauma. Image by YeeLey /Pixabay

Trauma causes inheritable changes to the DNA that can make the children and children’s children of trauma survivors more prone to drug abuse, disease, and mental disorders. Our parents or grandparents grew up during the Second World War and many experienced terrible things in that time. Bombings, hunger, the loss of friends, family members, and their homes, or they had to participate in war itself. These experiences surely were traumatizing, especially to those, who were still children at the time. This means that the current generation may still be affected by the war.

Shortly before the end of the Second World War, a famine plagued the west Netherlands, as the Nazis prohibited food supply from farm towns to this densely populated area. Toward the end of the war, people’s daily calory intake was reduced to 1300 kcal or less. Not only did this time increase the mortality rate, it also affected the generations to follow. Especially children of those who were exposed to famine while growing in their mother’s wombs, experienced health issues. They had an increased risk to suffer from cardio-vascular disease and obesity, but also psychological problems such as schizophrenia, depression, bipolar disorders, or antisocial personalities. Thus, not only psychological, but physical trauma can be passed on to future generations.

How trauma can be inherited

Our appearance, health, and to some extend behavior depend on the makeup of our genetic material, the DNA, which we inherited from our parents. DNA is like the blueprint to building humans and other beings (as also described here). Environmental factors, such as lifestyle and trauma can impact the readability of this blueprint, like a coffee stain on the document. The information is still there, but it cannot be read anymore. The same can occur the other way around, someone removed a “do not use” sticker and this part of the blueprint is suddenly readable. Both scenarios can have serious consequences, since it is important for healthy development that some parts of the blueprint can be used continuously, while others may only be readable when needed. If the blueprint is copied – as is the case with the formation of sperm and egg cells – the coffee stain is also copied or the “Do not use” sticker left out. The process of changing the readability of the blueprint is called epigenetics, and these changes can be inherited.

Children and grandchildren of holocaust survivors were more often referred to psychiatric clinics than other population groups, with grandchildren being overrepresented up to three hundred per cent among clinic patients. Studies on holocaust survivors and their children also showed that they have increased levels of stress hormones in their blood. This may cause them to feel stress much easier than non-traumatized people, which makes it likely for them to experience anxiety disorders.

Severity of trauma

How strongly horrific events affect a person depends on genetic, epigenetic, and environmental factors. This is true for people who inherited trauma, but also the first generation, which made the experience. Possible causes range from bullying, divorce of parents, neglect, and abuse, to natural disasters, injuries, and war. As these occurrences are quite common, so is trauma. About sixty per cent of all US citizens report to have experienced a traumatizing event during childhood.

Whether the trauma was induced physically or mentally influences the effects on later life. Physical trauma mostly, but not exclusively, results in physical problems, such as diabetes, cardio-vascular disease, or gastrointestinal problems. Whereas mental abuse often causes PTSD, anxiety, depression, substance abuse, eating disorders, and other problems.

Tragically, parents who suffered from trauma can unwillingly traumatize their children due to neglect and abuse. Research shows that traumatized parents tend to be emotionally distant toward their child. They can be less warm, less supportive, but also unable to handle conflicts, or even be violent. Scientists found that this kind of behavior is damaging for a child’s psyche. This way, emotional damage can be passed on through generations, even when it is not inherited via the DNA.

Trauma is not necessarily passed on

It almost appears counterintuitive that nature would weaken people when they have to go through hard times. But at least the hereditability of certain disorders is moderate: PTSD, depression, and low resilience can be passed on to varying extends but are never passed on one hundred percent. Strikingly, some offspring of trauma survivors are even more resilient than the average person. As if the epigenetic changes were to help them adapt to the harsh conditions their parents were exposed to. It is not completely clear how the effects can vary, but most certainly, the environment plays a role as well. The epigenetic changes may only cause negative effects when a person is also faced with certain types of stressful situations.

We can all count ourselves lucky if we have not experienced war in our own lifetime, when already the imagination of what our ancestors had to go through is painful. Even worse so, after the end of the Second World War, people still had the suck it up mindset, most of them suffered in silence. But talking helps, research finds. Especially children benefit from early interventions, such as speech therapy.

Many researchers in this field see opportunities for early intervention, when trauma is known to have occurred, whether direct or inherited. Trauma inflicted by abusive behavior toward a child, could for instance be counteracted by family counseling. Scientists also hope to find chemical treatments to reverse epigenetic changes. It will be impossible to prevent horrible things to happen to people, but it may be possible to prevent that it is passed on to others.  


Most important references:

Kyle, U. G., & Pichard, C. (2006). The Dutch Famine of 1944–1945: a pathophysiological model of long-term consequences of wasting disease. Current Opinion in Clinical Nutrition & Metabolic Care9(4), 388-394.

Sigal, J. J., & Weinfeld, M. (1989). Trauma and rebirth: Intergenerational effects of the Holocaust. Praeger Publishers.

Sangalang, C. C., & Vang, C. (2017). Intergenerational trauma in refugee families: a systematic review. Journal of immigrant and minority health19(3), 745-754.

Fossion, P., Rejas, M. C., Servais, L., Pelc, I., & Hirsch, S. (2003). Family approach with grandchildren of Holocaust survivors. American journal of psychotherapy57(4), 519-527.

Harachi, T. W., Choi, Y., Abbott, R. D., Catalano, R. F., & Bliesner, S. L. (2006). Examining equivalence of concepts and measures in diverse samples. Prevention Science7(4), 359-368.)

Kellermann, N. P. (2013). Epigenetic transmission of holocaust trauma: can nightmares be inherited. The Israel journal of psychiatry and related sciences50(1), 33-39.

Jiang, S., Postovit, L., Cattaneo, A., Binder, E. B., & Aitchison, K. J. (2019). Epigenetic modifications in stress response genes associated with childhood trauma. Frontiers in psychiatry10, 808.

Morgan, A. J., Rapee, R. M., & Bayer, J. K. (2016). Prevention and early intervention of anxiety problems in young children: A pilot evaluation of Cool Little Kids Online. Internet interventions4, 105-112.

Pina, A. A., Zerr, A. A., Villalta, I. K., & Gonzales, N. A. (2012). Indicated prevention and early intervention for childhood anxiety: A randomized trial with Caucasian and Hispanic/Latino youth. Journal of consulting and clinical psychology80(5), 940.

Published by Katrin Heidemeyer

Katrin Heidemeyer ist Doktorandin im Bereich Biochemie an der Wageningen University and Research. Durch ihre Arbeit möchte sie das Wissen über die Spezifität von Hormon-Signalen in Pflanzen erweitern. Da ihre Interessen über Pflanzenbiologie hinausreichen, schreibt sie in ihrer Freizeit über diverse Themen. Von Ernährung zu Psychologie, der Neugierde sind keine Grenzen gesetzt.

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