Most of us who suffer from anxiety, depression or other disorders may see hints of it in the family tree. There may be stories of distant relatives who, in the age before widespread diagnosis and treatment, were referred to as “eccentric,” or who “had a nervous breakdown.”
On an overnight train trip through Russia, more than one of my Jewish American traveling companions reported having holocaust nightmares induced by the train trip. At the time, I didn’t give much credence to their stories.
However, science is beginning to find evidence that our bodies can inherit memories without altering DNA sequencing.
Victoria Hughes wrote in the journal Nature, “People who were traumatized during the Khmer Rouge genocide in Cambodia tended to have children with depression and anxiety, for example, and children of Australian veterans of the Vietnam War have higher rates of suicide than the general population.” (3)
It is a theory long accepted in the field of psychology, and now there's evidence, that the experiences of grandparents and great-grandparents could possibly result in genetic mutations that affect our behavior today. (2)
Scientists have previously found in research that female rats could change the DNA passed on to their children. (1) New studies show that trauma also affects the genes that male rats pass on. (3)
The root of the genetic inheritance of trauma seems to begin with the molecular processes involved in non-genetic inheritance of behavioral symptoms. (2) Short RNA molecules play a key role. These microRNAs have regulatory functions, such as controlling how many copies of a particular protein are made. (2)
In the study, young mice were exposed to traumatic conditions in early life, and then compared to with non-traumatized mice. The traumatized mice expressed measurably different behaviors, including losing their natural (and protective) aversion to open spaces and bright light. The mice also had depressive behaviors. (2)
Researches in the Zurich study discovered that the traumatized mice had alterations in the amount of several microRNAs in the blood, brain and sperm (1) showing that genetic trauma can be inherited from both mother and father.
In addition, it was shown that trauma also impacts metabolism in offspring, affecting up to the third generation. "With the imbalance in microRNAs in sperm, we have discovered a key factor through which trauma can be passed on," explained Isabelle Mansuy, professor at ETH Zurich and the University of Zurich. (2)
In a 2011 TED talk, Annie Murphy Paul discussed how pregnant women exposed to the World Trade Center attack on 9/11, and who subsequently developed PTSD, bore children who had a biological marker of susceptibility to PTSD. So children born to mothers suffering PTSD, especially if they were traumatized in the third trimester, are more likely to develop the disorder. (1)
Another, unrelated study gives credence to the long speculated upon relationship between Holocaust survivors and trauma in their descendants. A chemical coating may mark chromosomes of children of Holocaust survivors, giving them a sort of biological memory of the horrors their parents endured. (4)
Scientists are speculating that our phobias — snakes, spider, small places — may also have an epigenetic source. (5)
Sources:
1) Trauma: Our Genetic Inheritance. Tedx.Amsterdam. Retrieved January 11, 2016.
http://tedx.amsterdam/2014/08/trauma-can-inherited
2) Hereditary trauma: Inheritance of traumas and how they may be mediated. ScienceDaily.com. Retrieved January 9, 2016.
http://www.sciencedaily.com/releases/2014/04/140413135953.htm
3) Sperm RNA carries marks of trauma. nature.org. Retrieved January 9, 2016.
http://www.nature.com/news/sperm-rna-carries-marks-of-trauma-1.15049
4) Epigenetic transmission of Holocaust trauma: can nightmares be inherited? NIH.gov. Retrieved January 15, 2016.
http://www.ncbi.nlm.nih.gov/pubmed/24029109
5) The Family Tree Of Phobia: Epigenetics Explains How We Inherit Fear From Our Ancestors. MedicalDaily.com Retrieved January 13, 2016.
http://www.medicaldaily.com/family-tree-phobia-epigenetics-explains-how-we-inherit-fear-our-ancestors-264134
Reviewed January 14, 2016
by Michele Blacksberg RN