Meeting the Ghosts in my DNA

Using family tree research to understand my epigenome

When I was a kid and would visit my grandma, I was interested in why she had stacks of used margarine containers in a cupboard in the kitchen. I learned from my dad about how my grandma had lived through the Great Depression, and how she saved things that might be useful. I loved my grandma dearly, and I understood implicitly what my dad was getting at because I also saved things. I would save my Halloween candy for months and I had various collections of rocks, baseball cards, and more.

Could I have inherited my hoarding tendencies from my grandma, even though she acquired her behavior during her lifetime? The science of epigenetics suggests just this.

As a family tree researcher, I love to find stories about my ancestors. I do it out of curiosity. I love to find photos and use documents to build a profile of each person. Sometimes in the documents or stories, I find evidence of hard times. All of my grandparents lived through the Great Depression. A great-grandmother was orphaned and experienced severe burns as a child. Many of my ancestors experienced war, immigration, poverty, abuse, alcoholism, or sometimes combinations of these. Those are just the stories that I know about.

What if the way my ancestors responded to those experiences could be passed on genetically? It might make building a family tree with stories a necessary component of any process of coming to self-understanding and self-care.

Many therapists use a tool called a “genogram” to tease out the deep history of their clients. The genogram maps events and relationships onto a family tree, as a starting point for understanding and healing.

I always assumed that my dad’s thriftiness was a result of growing up with his mother as an influence. Although that still might be true, the science of epigenetics is proposing that such behaviors might also be coded into the way our cells express the information found in the DNA.

Hank Green gives a great overview of epigenetics.

Epigenetics is based on the idea that although each cell contains a complete set of our DNA, the expression of that DNA depends on a number of factors. For example, in the very early stages of embryonic development, stem cells need to differentiate into brain cells, lung cells, muscle cells, and so on. They do this through the process of epigenetics. “Epi” means “on top of,” so “epi-genetics” is a word used to describe a number of actions that happen to the DNA in a cell to decide which genes to express and when.

One mechanism of epigenetics is when a “methyl group” attaches to the DNA at a certain section, blocking the ability of those genes to be read. The methylation process can act as a dial to turn up or down gene expression. Also, micro or small RNA can serve the same function, as well as the way that the DNA strands wrap around certain proteins called histones, which can make certain parts of the genome unavailable for expression.

Moshe Szyf describes methylation and epigenetics, and Courtney Griffins speaks to the mechanisms of epigenetics.

It is through the various epigenetic processes that cell differentiation takes place in the developing embryo. But that is not the only time that epigenetic effects can act on DNA.

Studies have shown that exposure to certain chemicals can leave an epigenetic fingerprint on the way our cells express the information found in our DNA.

Other studies have shown that Adverse Childhood Experiences (ACEs) can affect the epigenetics of people. Given how common ACEs are in our society (a study by Kaiser Permanente found over 60% of participants had at least one ACE, and 20% had five or more), and how many potential toxins exist in our environment, each individual can build a distinct epigenome over the course of their lifetime.

The body keeps a record of the experiences that people have. This process is normal and human and does not make any of us “broken.”

Scientists long thought that none of the epigenetic tags that build-up for people during their lifetime due to exposure to toxins or ACEs or other experiences are passed on to their children. It was assumed that the DNA was wiped clean of methyl groups and such through the reproductive process, and each baby started fresh.

However, recent studies suggest that some epigenetic tags might be “sticky” and get passed on to the next generation. In one famous study, researchers Brian Dias and Kerry Ressler of Emory Univerity studying rats combined an electric shock with the smell of cherry blossoms. The rats came to exhibit a startle response every time the scent of cherry blossoms was introduced to their cages, even when the shock was not applied. What amazed researchers was that the offspring and grand offspring of those rats exhibited the same behavior, even when raised by other rat parents which had not experienced the electric shocks.

This study defied all the science at the time. One should not be able to pass on behavior through inheritance. But yet, here it was. Epigenetics had helped behavior jump to the next generations.

Oded Rechavi describes how epigenetics can help us understand how memory can be inherited.

Scientists have found that the epigenetic fingerprints of the effects of different toxins were different. They can look at the methylation patterns of the tags on the DNA and identify the toxins that the individual was exposed to. What amazed the scientists was that they could identify the methylation patterns for several generations after the exposure, despite no continued toxin exposure to the offspring. What happened to our grandparents has echos in our epigenomes.

Researcher Michael Skinner gives a great overview of epigenetics and how the toxins experienced by grandparents and great-grandparents can have effects on future generations.

It is relatively easy to study epigenetics in the laboratory setting with animal test subjects (putting aside for the moment the legitimate ethical questions about animal testing), but human lifespans are too long, and ethics forbid such experiments on humans. However, scientists have been able to study several “natural experiments,” including analyzing the descendants of men who were imprisoned at the notorious Andersonville Prison during the Civil War and looking at the descendants of people who lived through famine during World War II. In each case, statistically significant health and mortality effects turned up in the children and grandchildren of those affected.

Some scientists speculate that the “stickiness” of epigenetic tags could be a way for a family or population to pass on adaptive behaviors or biological adaptation to the environment. For example, anxious rats might confer an advantage to their offspring, if the environment continues to be dangerous. In humans, if there were a way to express thriftiness behavior through epigentic tags, that would be adaptive for a population that experiences continued scarcity. Children would be born ready to save margarine tubs.

Despite sometimes being adaptive, some of the adaptive responses are not healthy for people, especially people who are not experiencing the ongoing environmental stressor that triggered the initial response. For example, heightened stress and high cortisol levels might be necessary to respond to a threat through fight or flight, but when there is no threat, the stress response can be hard on a person’s body and mental health.

In his recent book My Grandmother’s Hands, author and therapist Resmaa Menakem writes about the need to heal from what he calls ”transgenerational trauma,” and he gives readers body-centered practices to release the trauma. If epigenetic tags can be added onto the genome, then surely they can be removed as well. In his work with couples and with military veterans experiencing PTSD, Menakem has seen that healing is possible for people who have chronic patterns triggered by past traumatic events.

A good introduction to Resmaa Menakem can be found at the On Being podcast. He gives us hope for healing. The past is not necessarily the future. If the body keeps score of everything that happened to us as children and retains behaviors from our ancestors, then it also keeps score of all the love and nurturing we give and receive. This is also normal and human.

Brandy Wells speaks of the role of family trees and epigenetics in caring for children as a response to intergenerational trauma.

In one study of rats, researchers at McGill University took rat pups away from their mothers and reared them without the physical contact of a mother, which would have consisted of a lot of licking and physical touch. The researchers found that the rats which did not get licked had many adverse health and behavioral outcomes compared to the rats which received typical amounts of physical nurturing. Specifically, the unlicked rats were more anxious than the licked rats and the stress led to shorter lifespans.

When the scientists studied the epigenome of the rats that did not get licked, they found much more methylation within the genome, which had the effect of suppressing genetic expression. Researchers suggested that the physical nurturing of the rat mothers had “de-methylation” effects, and they tested this hypothesis by injecting de-methylation chemicals into anxious rats, which calmed them down, and also injecting methyl groups into calm rats, which made them anxious.

This rat-licking research speaks to Resmaa Menakem’s experience as a therapist using body-centered practices to support healing for trauma survivors. Our experiences and interactions can modify our epigenome.

It looks like our genetic expression is fluid and can be influenced. This doesn’t just apply to people who have experienced PTSD or other trauma. We could all benefit from nurturing touch and supportive listening.

As a genealogist, my new understanding of epigenetics and body-centered healing practices will have me thinking about ways to move some of my own chronic behavior patterns, which may be echoes of my own ACEs or the experiences of my ancestors.

As a society, in the United States, we can use the epigenetic lens to look at the many traumas in our collective past. We can look at the potential epigenetic effects of the horrors of the attempted genocide of Indigenous people, the trauma of enslavement and systemic oppression on Black Americans, the impact of wars and economic depressions on families, and more.

Each of these collective experiences has the potential to be healed and transformed, and now that we know that trauma can be retained and passed on through many generations, we bear a responsibility to stop it from being transferred to the next generation.

The final lesson is that we need to do what we can to prevent present-day trauma from happening. It needs to stop here. We need to support healthy families. We need to find ways to systemically avoid inflicting new trauma on groups of people (ie. interrupting ongoing systemic racism). We need to fix our broken prison system which inflicts trauma on every inmate. We need to find ways to avoid war. We need to adequately fund mental health support and addiction recovery.

Thomas Austin in a short TED talk sums it up by saying that although we are not responsible for what happened before we got here, we are absolutely responsible for what happens next.

Thank you for reading. You can find more stories from my journey as an amateur genealogist here.

© Andrew Gaertner, 2022