JUN 16, 2019 3:20 PM PDT

Can We Inherit PTSD from Our Parents?

WRITTEN BY: Annie Lennon

We often think of the negative byproduct of trauma, Post Traumatic Stress Disorder (PTSD), as a personal experience. But research now suggests that PTSD may not be an individual experience after all. In fact, it may be inherited.

Studies have shown that experiencing trauma may leave a chemical mark on a person’s genes, which is then passed down to future generations (Pembrey: 2013). Known as epigenetic inheritance, although the process does not directly damage the genes, it may instead alter the mechanism by which they are expressed, thus producing a change in someone’s physical appearance or behavior.

There are many studies that provide evidence for this theory. For example, researchers found that children born to women who experienced trauma during the Rwandan genocide were more likely to exhibit characteristics associated with Post-Traumatic Stress Disorder (Perroud: 2014). More than this, research has also shown that children born to people traumatized by the Khmer Rouge in Cambodia were more likely to have depression and anxiety. Furthermore, the children of Australian veterans of the Vietnam war had significantly higher rates of suicide than the general population (TED: 2014). Similar findings also exist for Holocaust survivers and their children (Kim: 2018).



Animal studies also point towards epigenetic inheritance. In one study, researchers tested this by exposing rats to a certain smell before an electric shock. Quicky, they adapted a fight or flight response to the smell, and this response remained present in future generations of these rats, even though that had no personal experience of having developed the fight or flight response to the smell themselves (Dias: 2013).

Despite such evidence justifying epigenetic inheritance, the theory is nevertheless controversial. Critics argue that although correlations may be made between certain behavioral tendencies and trauma inflicted in previous generations, the biological workings of the process are unknown, and may be implausible. They argue that, given the genetic shuffling that occurs following conception when the sperm and egg meet, there is no physical evidence that marks of trauma survive (Carey: 2018).

To understand this further, several theories have been proposed, although none with certainty. From studying epigenetic inheritance in mice, Dr. Oliver Rando from the University of Massachusetts has suggested that a male’s experience of stress and external environment may impact their small RNAs, necessary for sperm production. As the functions and impacts of small RNAs are still being researched however, it is difficult to provide any certainty (ibid.).

 

Beyond purely biological explanations,  more philosophical explanations for inherited trauma may be able to shed some light on the phenomenon. Collective Unconsciousness, a theory developed by psychiatrist and psychoanalyst, Carl Jung, explains that humans and animals are born with a subconscious collection of knowledge and images inherited from their ancestors that may only be activated by certain environmental triggers (Journal Psyche).

An example of this theory is a study analysing children’s first exposure to a rabbit and a snake. Of the 100 children studied, all of them responded with a degree of fear when exposed to the snake, refusing to touch it. With the rabbit however, only two children responded with the same degree of fear. Following Jung’s theory, exposure to a rabbit or snake must have activated the children’s subconscious and innate memory from common ancestors who had traumatic experiences when encountering these animals during their lifetimes (Study.com).

To conclude, epigenetic inheritance may be responsible for many subconscious behavioral triggers we have. This means that, although we may not have experienced trauma ourselves, we may inherit certain markers from our parents which leave us more susceptible to certain traits- from fear to depression and PTSD. Although correlational theories and studies tend to point towards this conclusion, our knowledge of human biology is still insufficient to confirm it.

 

Sources

 

Pembrey, Marcus E. et al.: Research Gate 

Perroud, N. et al.: PubMed 

Dias, Brian G. et al: Nature 

TED

Kim, Brenda Kelley: Labroots

Carey, Benedict: NY Times

Study.com 

About the Author
  • Science writer with keen interests in technology and behavioral biology. Her current focus is on the interplay between these fields to create meaningful interactions, applications and environments.
You May Also Like
OCT 14, 2020
Neuroscience
Researchers Pinpoint Neurons Affected by Epilepsy
OCT 14, 2020
Researchers Pinpoint Neurons Affected by Epilepsy
Video: Explains in more detail the different receptors affected by epilepsy. Researchers at the University of Copenhagen ...
OCT 27, 2020
Immunology
The Genetics of Skin Inflammation, Seen With Unprecedented Clarity
OCT 27, 2020
The Genetics of Skin Inflammation, Seen With Unprecedented Clarity
A recent study published in Immunity details MIT scientists’ exploration of the underlying mechanisms of inflammat ...
DEC 13, 2020
Genetics & Genomics
Investigating the Many Nuclei in Muscle Cells
DEC 13, 2020
Investigating the Many Nuclei in Muscle Cells
Researchers led by Professor Carmen Birchmeier at the MDC have used a cutting-edge tool to learn more about different nu ...
DEC 29, 2020
Microbiology
How CRISPR Can Help Create a Vaccine for a Common Parasite
DEC 29, 2020
How CRISPR Can Help Create a Vaccine for a Common Parasite
The parasite Toxoplasma gondii is thought to infect a third of the people on the planet as well as a wide range of other ...
JAN 03, 2021
Genetics & Genomics
Exploiting Genetic Vulnerabilities in Cancer Cells
JAN 03, 2021
Exploiting Genetic Vulnerabilities in Cancer Cells
Genetic errors can drive cancer, often when critical genes like those that control cell division and proliferation becom ...
JAN 06, 2021
Genetics & Genomics
Junk DNA Helps Control the Body Clock
JAN 06, 2021
Junk DNA Helps Control the Body Clock
Our bodies run on a kind of molecular clock, which helps regulate and time certain functions beyond just waking and slee ...
Loading Comments...