Yet another study by the Brain Research Institute of the University of Zurich in 2011 exposed baby mice to stressful situations by separating them from their mothers.[2] The abandoned mice experienced anxiety and depression—which, right, seems obvious. What was shocking was how this separation affected future generations of mice. When the traumatized mice had babies, and then when their babies had babies, the scientists never separated them from their parents. They led perfectly content, nurtured little mouse lives. But for three subsequent generations, the anxiety and depression persisted.
There is real scientific evidence that the traumas we experience can be passed on to our children and even our grandchildren. DNA, of course, is the genetic code that determines the shape of our nose, our eye color, our likelihood to contract certain diseases. So when our body is making and remaking itself, every cell in our body actually “reads” our DNA and uses it as a blueprint for what to build. But not every cell reads the entire blueprint—the whole, long string of DNA. Inside each cell is both our DNA—or our genome—and the epigenome, a layer of chemical markers that sits on top of our DNA. The epigenome is like a SparkNotes for the cells—it flags which genes our cells really need to read. So the epigenome helps decide which genes actually get represented by our bodies. It turns certain genes on and other genes off. Both the genome and our epigenome are passed down generationally.
The stuff we think of when we think about DNA—nose shape, eye color—only comprises about 2 percent of our total DNA. The other 98 percent is called noncoding DNA, and it is responsible for our emotions, personality, and instincts. The epigenome on top of noncoding DNA is very sensitive to stress and the environment. When a body adapts to constant, overwhelming stress—not a car accident or a bad flu, but long-lasting trauma—the epigenome changes. Trauma can turn on a gene that responds to the smell of cherry blossoms, for example. Or turn off a gene that regulates our emotions. It might turn on a gene for fear.
In 2015, Rachel Yehuda, director of the Traumatic Stress Studies Division at the Icahn School of Medicine at Mount Sinai, conducted a study where she analyzed the FKBP5 gene, which helps control stress regulation.[3] The study showed that Holocaust survivors and their descendants shared the same epigenetic tags on the very same part of the FKBP5 gene. Then Yehuda compared those genes with those of Jewish people who lived outside of Europe and did not suffer through the Holocaust. Their epigenetic tags weren’t altered. It was clear that the trauma of experiencing the Holocaust specifically created DNA methylation on the FKBP5 gene of survivors…and their children.
Even more surprising, Michael Meaney at McGill University has studied whether it’s possible to reverse this DNA methylation.[4] He had a population of mice whose mothers didn’t lick them very much growing up. These mice essentially had distracted, neglectful mothers and grew up anxious. So Meaney injected a solution into the brains of these anxious mice that could pull off the epigenetic markers. And…it worked. Afterward, the mice weren’t anxious anymore. Their stress response was completely normal.
Unfortunately, there is no brain injection that works for humans. And even if there was, what might the consequences be? If I was to remove the wiring that’s been written over generations, it’d be like restoring the factory settings on a computer. And what would my default settings be? Who would I be?
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Every adaptation our brain makes is an effort to better protect our bodies. Some of these backfire—the deadly result of an overactive stress response. But some might actually be advantageous to our health.
The Swedish town of ?verkalix has the most comprehensive and oldest birth, death, and crop records in the world. Their records go back generations—a remarkably rich data set. And in analyzing this data set, scientists found some fascinating correlations. There were good and bad years for the crops in ?verkalix and some particularly bad years where families were forced to go hungry. But scientists discovered that when children suffered starvation between the ages of nine and twelve, their grandchildren would on average live thirty years longer. Their descendants had far lower rates of diabetes and heart disease. On the other hand, when children were well-fed during those ages, their descendants were at four times the risk for heart attacks and their life expectancy dropped. In some strange way, the trauma of starvation changed descendants’ genes to be more resilient. Healthier. More likely to survive.[5]
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Clearly, it wasn’t just my ruthless nurture that had shaped me into who I was, though who knows what kind of rampant methylation savaged my epigenome during my beatings and assaults. Beyond that, every cell in my body is filled with the code of generations of trauma, of death, of birth, of migration, of history that I cannot understand. Just piecemeal moments I collected from Auntie over the years.
My family tried to erase this history. But my body remembers. My work ethic. My fear of cockroaches. My hatred for the taste of dirt. These are not random attributes, a spin of the wheel. They were gifted to me with purpose, with necessity.
I want to have words for what my bones know. I want to use those gifts when they serve me and understand and forgive them when they do not.
But now I turn my head like the Sankofa bird and see nothing. I want to reclaim my stolen past. I need it to write my future.
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Auntie died suddenly, just a couple of months after I last visited her and she told me I was not the favorite after all. As much as I’d like to, I cannot ask her further questions about my family history. But I do still have recordings of our interactions from that visit. I dig up my old hard drives and dive back into them, transcribing whatever I can understand, leaving out the Cantonese bits. I supplement these recordings with oral histories I find stored in Singapore’s National Archives to learn the details of what bitterness my family was forced to eat.
I learned that Auntie and my grandmother had not just survived World War II, as I’d previously thought. There was another war they lived through, a secret war that history would prefer to forget.
Under Japanese occupation of Malaysia during WWII, a Communist guerrilla force grew in the jungle. With half a million members, they called themselves the Malayan National Liberation Army, or MNLA, and they wanted freedom from the oppressive rule of colonization, which at this point had rocked the country for hundreds of years—first the Portuguese, then the Dutch, then the British, then the Japanese.