But what if our experiences of being bullied did a lot more than just saddle us with some serious psychological baggage? Well, to answer that question, a group of researchers from the UK and Canada decided to study sets of monozygotic “identical” twins from the age of five. Besides having identical DNA, each twin pair in the study, up until that point, had never been bullied. You’ll be glad to know that these researchers were not allowed to traumatize their subjects, unlike how the Swiss mice were handled. Instead, they let other children do their scientific dirty work. After patiently waiting for a few years, the scientists revisited the twins where only one of the pair had been bullied. When they dropped back into their lives, they found the following: present now, at the age of 12, was a striking epigenetic difference that was not there when the children were five years old. The researchers found significant changes only in the twin who was bullied. This means, in no uncertain genetic terms, that bullying isn’t just risky in terms of self-harming tendencies for youth and adolescents; it actually changes how our genes work and how they shape our lives, and likely what we pass along to future generations. What does that change look like genetically? Well, on average, in the bullied twin a gene called SERT that codes for a protein that helps move the neurotransmitter serotonin into neurons had significantly more DNA methylation in its promoter region. This change is thought to dial down the amount of protein that can be made from the SERT gene—meaning the more it’s methylated the more it’s “turned off.” The reason these findings are significant is that these epigenetic changes are thought to be able to persist throughout our lives. This means that even if you can’t remember the details of being bullied, your genes certainly do. But that’s not all these researchers found. They also wanted to see if there were any psychological changes between the twins to go along with the genetic ones that they observed. To test that, they subjected the twins to certain types of situational testing, which included public speaking and mental arithmetic—experiences most of us find stressful and would rather avoid. They discovered that one of the twins, the one with a history of being bullied (with a corresponding epigenetic change), had a much lower cortisol response when exposed to those unpleasant situations. Bullying not only turned those children’s SERT gene to low, it also turned down their levels of cortisol when stressed. At first this may sound counterintuitive. Cortisol is known as the “stress” hormone and is normally elevated in people under stress. Why, then, would it be blunted in the twin who had a history of being bullied? Wouldn’t you think they would be more stressed in a heightened situation? This gets a little complicated, but hang tight: As a response to the persistent bullying trauma, the SERT gene of the bullied twin can alter the hypothalamic-pituitary-adrenal (HPA) axis, which normally helps us cope with the stresses and tumbles of daily living. And according to the scientists’ findings in the bullied twin, the greater the degree of methylation, the more the SERT gene is turned off. The more it’s turned off, the more blunted the cortisol response. To understand the sheer depth of this genetic reaction, this type of blunted cortisol response is also often found in people with post-traumatic stress disorder (PTSD). A spike of cortisol can help us through a tough situation. But having too much cortisol, for too long, can short-circuit our physiology pretty quickly. So, having a blunted cortisol response to stress was the twin’s epigenetic reaction to be being bullied day after day. In other words, the twin’s epigenome changed in response to protect them from too much sustained cortisol. This compromise is a beneficial epigenetic adaptation in these children that helps them survive persistent bullying. The implications of this are nothing short of staggering. Many of our genetic responses to our lives work in such a fashion, favoring the short over the long term. Sure, it’s easier in the short term to dull our response to persistent stress, but in the long run, epigenetic changes that cause long-term blunted cortisol responses can cause serious psychiatric conditions such as depression and alcoholism. And not to scare you too much, but those epigenetic changes are likely heritable from one generation to the next. If we’re finding such changes in individuals like the bullied twin, then what about traumatic events that affect large swaths of the population?
Even if we no longer have memories of being bullied, our genes will remember it. This means that there can be lasting damage to even their descendants. Imagine the lasting damage this pandemic might have on the number of people and their genes.
