Magazine "Research" · Reading time approx. 10 min
"The grandmother's trauma is in the genes." It's a good line, and it isn't backed by evidence — at least not as stated. A look at what the research actually shows, and what that means for genogram work.
Three Levels That Often Get Confused
In counseling, this line comes up regularly. A client talks about her grandparents' experience of war and says, "It's in our bones." Sometimes the word epigenetics comes up too.
What people usually mean is actually three very different things. It's worth separating them before talking about evidence.
First, transmission through behavior and narrative. A mother who experienced hunger as a child relates to food differently. Her children pick up on this without anyone ever discussing it. This level is well studied and uncontroversial.
Second, psychodynamic transmission. What goes unspoken becomes a family rule. A topic is avoided, and everyone knows it's being avoided. This, too, is well documented clinically.
Third, the biological inheritance of acquired imprints. That is, the idea that an experience alters the germ cells in a way that gets passed on to children and grandchildren. This third level is the contested one.
In everyday language, all three blur into a single sentence. That's exactly where the problem starts.
The Study Everything Refers Back To
The most frequently cited work comes from Rachel Yehuda and colleagues. It appeared in Biological Psychiatry in 2016. The study looked at 32 Holocaust survivors and 22 of their descendants, focusing on a gene called FKBP5, which is involved in stress regulation. Researchers measured how strongly certain sites on this gene were chemically marked.
The result: survivors and their children showed differences in this marking compared with a control group.
A follow-up study by the same group appeared in the American Journal of Psychiatry in 2020, examining the maternal transmission pathway in more detail.
This is a serious line of research. But it isn't what popular reception has turned it into.
Why Experts Remain Cautious
Two years after the first study, Bernhard Horsthemke published a commentary in Nature Communications. His objection is fundamental: in humans, it's nearly impossible to rule out that an observed difference has other causes.
Children of survivors grow up in a particular environment. They hear particular stories, experience particular reactions, and often share diet and living conditions as well. All of that leaves traces. To prove genuine inheritance, one would have to rule out these influences — and in humans, that's practically impossible.
A 2024 review by Bird and colleagues in Frontiers in Epigenetics and Epigenomics continues this critical line.
Then there are the numbers. Thirty-two plus twenty-two people is a small sample. In small groups, random differences can easily look like a finding.
There's also a conceptual hurdle that's rarely mentioned. For something to be truly inherited, the change would have to occur in the germ cells and persist across multiple generations. Changes in body cells — blood cells, for instance, which are easy to measure — are not passed on. Much of what gets reported as "epigenetic inheritance" actually falls into this second category.
What Works in Mice but Not in Humans
In animal studies, the situation is different. There, environmental conditions can be controlled, generations arrive quickly, and researchers can track effects through to the third generation of offspring. Some findings there are replicable.
Transferring these results to humans is the leap that isn't supported. A laboratory mouse doesn't share stories, upbringing, or family secrets with its offspring. A human being does. What counts as clean evidence in animals becomes, in humans, just one of several possible explanations.
What This Means for the Genogram
None of this is discouraging for genogram work. Quite the opposite.
The genogram shows patterns. It shows that in three generations, a child left the family early each time. It shows that deaths in one line go unmentioned. It shows repetitions that no one notices as long as they're looking at only one generation.
What it doesn't show is the cause. A pattern in a genogram is an observation, not an explanation. That's precisely its strength: it makes something visible without already interpreting it.
The temptation to explain a visible pattern with a biological mechanism is strong. It leads to a dead end. Saying "that's epigenetic" ends the conversation. Asking "how was this passed on in your family" opens it.
Hypothetical case example: A woman comes to counseling and reports recurring anxiety. Her grandmother, she says, fled East Prussia as a child. "I've inherited this," she says. The genogram reveals that in three generations, the eldest daughter each time took on early responsibility for younger siblings. The counselor doesn't ask about genes, but about how anxiety was talked about in this family. The client remembers that her mother always stayed calm during thunderstorms — and that she herself, as a child, believed you weren't allowed to show fear. The pattern becomes something to talk about, without anyone having to settle the question of inheritance.
How to Talk About It
For practice, three ways of phrasing this can be distinguished.
Doesn't hold up: "Trauma is inherited epigenetically."
Holds up: "There are studies discussing epigenetic correlates. Whether and how this is transmitted across generations remains scientifically contested."
Useful in counseling: "A pattern shows up across three generations in your family. Let's look at how it might have been passed on."
The difference isn't merely linguistic. The first phrasing turns a person into a carrier. The third turns them into a participant who can understand and change something.
What Remains Open
Research continues, and that's a good thing. A clearer picture may emerge in ten years. It's equally possible that the third level proves nearly impossible to demonstrate in humans.
For counseling practice, this changes little. The clinically documented pathways — through behavior, through language, through what remains unsaid — are uncontroversial and entirely sufficient for the work. They also have one advantage: what was passed on through relationship can also be changed through relationship.
Sources
- Yehuda, R. et al. (2016): Holocaust Exposure Induced Intergenerational Effects on FKBP5 Methylation. Biological Psychiatry 80(5), 372–380.
- Horsthemke, B. (2018): A critical view on transgenerational epigenetic inheritance in humans. Nature Communications 9, 2973.
- Yehuda, R. et al. (2020): Intergenerational Effects of Maternal Holocaust Exposure on FKBP5 Methylation. American Journal of Psychiatry.
- Bird, A. et al. (2024): Transgenerational epigenetic inheritance: a critical perspective. Frontiers in Epigenetics and Epigenomics.