Can trauma, stress, and even nightmares be passed down from generation to generation?
Scientists say yes. A number of research finds that those who have been traumatized around the time of conception can pass on a DNA code to their offspring that results in a higher vulnerability to stress in their molecules, neurons, cells, and genes. Furthermore, this gene expression–a chemical coating upon the chromosomes–is strong enough to be passed on to a third generation, which means grandchildren have “a kind of biological memory” of what their grandparents experienced, according to studies.
This unconventional finding has led to a new scientific field of study called epigenetic inheritance. We’ve known for some time that the way parents raise their children impacts their human psychological development, affecting traits like later behavior, habits, personality, and aggressive tendencies. However, these environmental factors point towards child-rearing and are believed to be learned by the way parents interact with their children during formative years. On the other hand, the study of epigenetics finds genes are “tagged” or “marked” by past generations and can be switched on or off depending on environmental factors, such as trauma, stress, and even prenatal nutrition.
“Epigenetics is how your environment influences your genes,” Tara Swart, a senior lecturer at MIT, tells Fast Company:
The two most famous studies are about Holocaust survivors, so people who became pregnant around that time, and then people who became pregnant just before, during, or after the famine, which was in the Netherlands around the same time. Those [studies] showed that people who were in starvation or stress just before they got pregnant, because they had either switched on or switched off certain stress genes, the baby was actually born with a different stress threshold than its mother’s genes would have normally given it.
“[Researchers] reproduced it in animals and they looked at things like, if you give a rat an electric shock every time you give it a certain smell, like peppermint, then [findings] showed that its babies would get stressed when they smelled that smell even though they’d never had the electric shock,” explains Swart, co-author of the book Neuroscience for Leadership. “So they learned to get stress around that smell.”
In an influential study on epigenetic inheritance, researchers found that generations after the Second World War, offspring of Holocaust survivors continued to suffer from terrible nightmares of being “chased, persecuted, tortured or annihilated,” even though they were not around during the war.
The study says: “At these times, they suffer from debilitating anxiety and depression which reduce their ability to cope with stress and adversely impact their occupational and social function. It seems that these individuals, who are now adults, somehow have absorbed the repressed and insufficiently worked-through Holocaust trauma of their [parents and grandparents], as if they have actual inherited the unconscious minds” of those who survived.
Other studies on pregnant women who witnessed the 9/11 attacks on the World Trade Center found that similar “scars” on DNA were passed on to their babies, resulting in higher levels of the stress hormone, cortisol, in their children. Researchers also studied adults who were fetuses during the severe 1944 Dutch famine and found that their mental tests showed this group performed worse in dealing with competing distractions compared to others in their age group. Poorer performance on this kind of attention test is linked to advance aging.
So, what should be done now that we know trauma of previous generations can be passed down to future generations?
One study concludes: “. . . Even though such offspring might still be more or less influenced by their genes and despite their physiological predestination, they might realize that it’s up to them to decide what to do with all of it. Instead of succumbing to the emotional effects of the past tragedies, they might search and find some kind of personal transformation journey that gives new meaning to their legacy.”
As daunting as these studies are, it can help those suffering from past generation’s trauma to understand their weaknesses better. How should one deal with stress? How should one become more resilient when dealing with stress?
In her recent Neuroscience For Leadership class, Swart discussed different practices for re-balancing yourself to have a calmer mind, increased self-awareness, and thus a better ability to cope with stress. These practices range from the more widely known, such as meditation and yoga, to more offbeat ways, such as the “polar bear plunge”: popular in Nordic countries, you jump into icy cold water to “put yourself in complete stress, then allow your body to recover,” says Swart.
There are also practices of self-awareness where one deprives themselves of food or going to the bathroom for a certain amount of time to increase focus levels, says Swart. Whatever your approach is, know that you also have the ability to determine your fate and the fate of your successive generations.