LIVING IN GENERATIONS OF FEAR?
Can trauma genetically alter a generation? The emerging field of epigenetics is prompting questions about what we pass on to our children and grandchildren, writes the Citizen’s Tom Spears.
Kids may inherit more than we thought
There’s nothing particularly alarming about the aroma of acetophenone, a chemical whose sweet smell reminds people of almonds.
But for a set of mice in Atlanta, it became a source of fear. Brian Dias of Emory University repeatedly let them sniff the chemical, then gave them mild electric shocks, until the mice learned that the smell was a sign that something bad was about to happen.
But the real news came a generation later. The offspring of that first group of mice also reacted in fear at the smell of acetophenone, even though they had never experienced an electric shock themselves.
And their own offspring — now two generations removed from the shock experiment — also inherited a fear of the distinctive smell.
Dias has a broad and philosophical view of what human consciousness is. Raised in India, he is a faculty member of the Emory Tibet Science Initiative and teaches neuroscience to Tibetan Buddhist monks in India. He was recently on a panel discussing Consciousness — Perspectives from Western Neuroscience and Buddhist Philosophy with the Dalai Lama. (The session is on YouTube.)
It’s perhaps an ideal disposition for someone who is also trying to identify the nuts and bolts of an emerging field in consciousness.
It’s known as epigenetics — literally “beyond genetics” — and it’s raising such mind-bending questions as: Can we inherit fear? Can drug addiction pass down genetic effects to an addict’s children? Can extreme stress or trauma, on the scale of war or famine, re-shape an entire community, down through one or more generations?
In short, how much do our genes remember?
THE SCIENCE
You get a set of genes when you’re conceived; half from your mother, half from your father. That basic code never changes.
But genes are on chromosomes — strands of DNA — and chromosomes undergo physical changes throughout your lifetime.
One such change is called methylation. A small molecule called a methyl group, which is a little cluster of hydrogen and carbon atoms, attaches itself to points along the DNA.
This happens naturally during your life as you age, but under high stress, it can happen more frequently.
(That’s right: Stress can influence your DNA.)
Your roughly 20,000 genes have different jobs, and as you age the body can raise or lower their levels of activity, or even shut them off. The little methyl groups can affect this activity level.
This is where epigenetics comes into play.
Epigenetics applies to many areas of medicine — perhaps to all of them. In medicine, those examining epigenetics have mainly been examining how our genes are affected within one lifetime, because changes in how genes act can affect our health.
But there’s also growing evidence about heredity — that we pass down some changes we acquire during our lifetime to our children, and even to our grandchildren.
That’s where things get really interesting.
TRAUMA AND THE HOLOCAUST
Some epigenetics study has focused particularly on the ordeal of Jews during the Second World War.
In 2013, Israeli psychologist Natan Kellerman, wrote: “The Holocaust left its visible and invisible marks not only on the survivors, but also on their children.”
Survivors themselves often have altered levels of stress hormones, compared to other Jews of the same age.
In 2016, two New York City hospitals established that survivors’ children also had altered stress hormones — though not in the same form as the changes in their parents. The researchers suggested that the impact may make the younger generation less able to handle stress, and more prone to anxiety disorders.
Both the parents and children, meanwhile, showed changes to one specific gene associated with depression and post-traumatic stress disorder in patterns that differed from people whose families had escaped the Holocaust.
“Instead of numbers tattooed on their forearms, (children of survivors) may have been marked epigenetically with a chemical coating upon their chromosomes, which would represent a kind of biological memory of what the parents experienced,” Kellerman wrote.
“As a result, some suffer from a general vulnerability to stress while others are more resilient.”
Kellerman titled his article ‘Epigenetic transmission of Holocaust trauma: Can nightmares be inherited?’
It’s not all the stuff of inherited nightmares, mind you.
In passing on epigenetic effects to the next generation, the body may be trying to help the next generation adapt.
For instance, it has been theorized that changes passed on to the genes of children of famine survivors may help prepare the children to deal with famine in their own time. And it has been observed that while some children of Holocaust survivors appear prone to anxiety and depression, others are somehow made more resilient, as if their genes are preparing them to meet the troubles of their parents’ time head-on.
THE YIN YANG OF NATURE-NURTURE
Intergenerational epigenetics is not a clear-cut matter. It resides somewhere in the murky nature-nurture divide.
“It’s not only nature, it’s not only nurture. It’s both of them working together,” says Brian Dias.
For instance, not every descendant of a traumatized ancestor is likely to show effects of trauma.
“‘Descendant A’ finds himself in a really nurturing environment, socializing a lot, dieting well, all of the good stuff. The imprints (from the ancestor) might never manifest.” But if ‘Descendant B’ lives in a harsher environment, “then those imprints might manifest. So it’s all about context.”
Both descendants may have been genetically primed for a certain trait, but that “imprint” may only display outwardly in one because of other, social or environmental factors. Humans are complex. Scientists have been able to sidestep some of that complexity by using mice and rats in labs.
The Dias team transferred its mouse embryos into mothers that had not lived through any trauma, so the babies were raised by mothers with none of the previous generation’s memories.
And still, the babies inherited the memory.
CHEMICAL SOLUTIONS?
“The promise and the challenge for us with epigenetics is to understand when epigenetic marks are going to be expressed … and what can we do to reverse those?” Dias said.
If he’s right, then social intervention — could mean “those marks never see the light of day.”
But there’s more than just counselling on the table here.
Once methylation occurs, once a chemical “tag” has attached itself to a gene, it may not have to stay there.
Dias and others have suggested that if a marker can attach itself through a chemical process, it may also be possible to use chemistry — drugs — to strip it away again.
That would leave the gene in its original, unhampered form.
That means drug therapy could, for instance, someday undo the genetic damage left to children of survivors of the Holocaust, the damage that leaves them prone to anxiety or heart disease.
If so, that would also take away the mechanism that passes on damage to grandchildren.
Such research into epigenetic therapies — cleaning up your DNA — is underway today.
WHAT IFS ABOUND
For all its power and potential, these are the early days of intergenerational epigenetics.
These are the days of “what if.” But the what ifs are thought-provoking.
At play here is the idea that emotional trauma might be genetically, biologically passed down from one generation to the next: That emotional damage done to a person or a community can affect their descendants on a genetic level, altering their very DNA.
It would, seemingly, be a testament to the existence of community or even race.
If a community can be genetically defined or distinguished, somehow, by its collective trauma, in a way that sets it apart from other communities, biology would be affirming the differences between us due to our families and communities’ history.
Furthermore, research is underway to determine how it is possible to repair such damage, including whether chemicals could do the trick.
In some ways, the field opens a Pandora’s box of identity through the lens of biology.
But it has also been seized upon by social scientists, who are viewing it as a very different opportunity.
For them, it affirms the notion that how we treat individuals and communities can have a restorative benefit reflected in their genes.
Because if genetic damage can be wrought by experience and social factors, then surely bettering the circumstances in which people live can have the opposite, curative effect, which would be no less rooted in science and biology.
‘MANY SOCIAL SCIENTISTS FELT VINDICATED’
There is excitement in the social sciences about epigenetic effects. Sociologists and criminologists reject a purely biological explanation for social problems, the idea that some people are born criminals or genetically programmed to be social misfits. They prefer a model in which society shapes us, and improving a child’s social environment will help to mould a successful adult.
But the new theory offers the possibility that social behaviour can mould the next generation’s genes — for instance in the context where poverty or abusive parents may be responsible for genetic changes that a child will carry through their entire lives. Yes, it’s genetic — but the basic driving force is social. It’s catching on widely, say U.S. criminologists Brian Boutwell and J.C. Barnes.
“For the past few years, social scientists have been buzzing over a particular topic in molecular biology — gene regulation,” they write in an essay called Epigenetics Has become Dangerously Fashionable.
“Many social scientists felt vindicated by the findings (that children’s genes can be affected), assuming it represented a triumph of the ‘social’ over the ‘biological.’”
Social scientists have tended to reject the theory that a person can be criminal because of biology. But for them, epigenetics offers to put nurture back in the driver’s seat — even in cases where the roots of a person’s aggressive or criminal behaviour seem to begin in early childhood.
Boutwell and Barnes warn against pushing the field too far, too fast.
They write that “the most compelling evidence for transgenerational epigenetics is in rodents, not humans. We are fans of animal research, but … the strengths of it (fast reproductive cycles allowing for the study of numerous generations in a short window of time) may also curtail its applicability to humans in this particular case. Additionally, scientists can randomly manipulate a rodent pup’s exposure to different parenting/rearing strategies. But doing this with human babies would never fly with a university ethics committee.”
“When you can’t do experiments, you have to be very careful about something called confounding. Confounding is a pernicious problem that can make one thing look like it’s causing something else when, in actuality, it’s not. … Experiments deal nicely with this problem. Associational studies in humans, though, are much more vulnerable to it.”
INDIGENOUS EPIGENETICS?
A Canadian psychologist is right now studying how support for women at risk during pregnancy and when their children are young will protect the children’s DNA from epigenetic damage.
Richard Tremblay is a psychologist who grew up in Ottawa. His father, Wilf, played halfback and returned punts for the Ottawa Rough Riders and the Saskatchewan Roughriders between 1938 and 1951.
Richard became a professor at the Université de Montréal, and is also on the faculty of University College Dublin.
Ten years ago, he started looking for epigenetic effects that might be related to aggressive behaviour.
Recently, he has been looking at identical twins, who are conceived as a single cell but develop into individuals with differences.
“We are trying to make the association between the epigenetic marks and the behaviour,” he said, in other words those who are primed for certain traits and those who actually develop them.
In passing on genetic effects to the next generation, he cautions that both genes and the environment matter, and the two are tangled together.
And while this is not part of his study area, Tremblay agrees it’s possible that there may be epigenetic effects left by a particular Canadian trauma, the experience of Indigenous children in residential schools.
In studies of people who survived concentration camps in Europe, “there appear to be intergeneration effects. So yes, theoretically it makes sense that we could observe intergenerational effects” among Indigenous people following the residential schools years.
“Problems that we have in Canada are probably the best example of the worst that can happen to individuals. … There are most certainly epigenetic effects of a lot of things that have happened to them, and these effects are probably intergenerational. And to really solve the problem we will need massive support to these people,” focusing on women before they become pregnant and while their children are young.
That is what he is now doing with groups of Canadian and Irish women and children in disadvantaged neighbourhoods, in conjunction with economist Orla Doyle in Dublin. But he said it’s too early to tell whether supporting the mothers will change the gene expression in their children.
“If we want to change the world, if we want to change the transmission of these problems, we need to do preventive interventions very early in life. We’re talking about interventions that are environmental — the quality of the care the children are receiving.”
One criticism in the epigenetics field is that the studies show only “association.”
When a baseball flies out of a stadium, the cause is plain: The bat made good contact. That is cause and effect.
An association is a weaker relationship: two things are often seen together, but no one knows the mechanism of the cause, if there is one.
Without showing this cause-and-effect relationship, it’s harder to justify saying that experiences of parents are passed on to later generations’ genetic material.
NOT BUYING IT
At Western University, Anna Zajacova studies social determinants of health, and she brushes aside the suggestion that native youth in Canada are injured via epigenetics by the damage to past generations.
She says the cause “is not epigenetics. It is their own environment that they (today’s native youth) are growing up in. Those parents went through trauma. It’s not that they are bequeathing their children genetic crap. They are struggling and the kids are growing up in struggling households. That’s where your story is, but it’s a little less sexy than epigenetics.”
‘WE DON’T REALLY KNOW’
Dias’s colleague on the mice study was Kerry Ressler, professor of psychiatry and behavioural sciences at Emory School of Medicine in Atlanta.
“Knowing how the experiences of parents influence their descendants helps us to understand psychiatric disorders that may have a trans-generational basis, and possibly to design” forms of treatment, writes Ressler, professor of psychiatry and behavioural sciences at Emory.
Note that Ressler says psychiatric illnesses “may have a transgenerational basis.”
The word “may” crops up a lot when scientists discuss their work on inheriting the effects of our parents’ experiences.
All this is a long way from establishing that what the journal Nature calls “the sins of the father” are visited upon later generations in humans, who are not the same as lab mice.
“The short answer is: We don’t really know how much of this stuff goes inter-generationally in humans for sure,” Dias said.
In the meantime, Brian Dias is back in his Atlanta lab after having his annual “re-set.” The Emory group travels to India during the summers to teach physics, philosophy of science, neuroscience and biology to monks. It’s a science curriculum mandated by the Dalai Lama.
He and others are dealing now with the cause-and-effect problem. For instance, it is known that “tags” attached to our genes during our lifetime are scrubbed away during reproduction. So how could the next generation inherit them?
“These marks are scrubbed clean at two different stages — just after fertilization and when the germ cells (sperm and eggs cells) are being formed,” Dias said.
But he says recent work is showing that a few tags do get through, depending on their “loci,” or positions where they attach to our DNA. Some genes just don’t scrub completely. But why not? No one knows, he says, “and that I think will be a challenge for the future.”
This takes the whole field into the tough job of demonstrating the “mechanisms” at work — the nuts and bolts of how these molecules operate, so that a researcher can point to the precise bit of material attaching to a gene and being passed on to children, rather than looking only at the effects in laboratory animals or humans.
“The devil is going to be in the details.”
The short answer is: We don’t really know how much of this stuff goes intergenerationally in humans.