Intergenerational trauma refers to the apparent transmission of trauma between generations of a family. People who experienced adverse childhood experiences growing up, or who survived historical disasters or traumas, may pass the effects of those traumas on to their children or grandchildren, through their genes, their behavior, or both, leaving the next generation susceptible to anxiety, depression, hypervigilance, and other emotional and mental health concerns.

The memories of a traumatic experience stay with the individual who experienced it; the worldview it created in them, however, can be inherited by their children. Even young children, research has shown, detect and react to their parent’s anxiety cues. Studies of Holocaust survivors have found that while many resisted talking to children about their experiences, their worldview—that the world was a dangerous place where terrible things could happen at any time—affected their children’s outlook as well.

How is intergenerational trauma transmitted?
The mechanisms are still being studied. One way is that people who have experienced significant trauma may be more likely to have diminished attachment skills, have less patience as parents, and generally communicate messages and lessons to their children that are rooted in stress or anxiety. Research has shown that children raised by parents who experienced multiple adverse childhood experiences such as emotional, physical, or sexual abuse; emotional or physical neglect; or parental separation or divorce are more likely to experience the effects of that adversity themselves.

Can sensitivity to traumatic cues be inherited?
Studies suggest that it can be. For example, when mice were conditioned in the lab to fear a certain smell, the succeeding two generations displayed a high sensitivity to the same smell, as well as increased receptors for detecting it.

Can genetic changes caused by trauma be passed on to children?

Epigenetics researchers, who study how the environment and other external factors, including trauma, can change the way one’s genes are expressed, propose that when trauma affects the expression of genes in an individual, those changes can be transmitted to their child. However, the evidence for this transmission is limited, and further research is required to establish how it may occur.

What research has been done on intergenerational trauma?
Research suggests that the children and grandchildren of people who survived traumatic events including the Holocaust, the Rwandan genocide, or the Khmer Rouge killings in Cambodia may have higher rates of anxiety, depression, and post-traumatic stress disorder than others. Specifically, research led by Rachel Yehuda of the Mount Sinai School of Medicine in New York found that the blood samples of people who had survived the Holocaust showed changes in the expression of genes involved in regulating stress response, as compared to peers who had not experienced the Holocaust directly—and that their children who were also not directly exposed showed similar effects.

Is there skepticism about intergenerational trauma?
Yes. Research into trauma inherited via epigenetics has so far been relatively limited, even the scientists conducting that work acknowledge that there is still a great deal to learn about the epigenetic transmission of trauma. There is, however, wide clinical acceptance of the idea that a parent’s traumatic experiences, especially abuse, can affect the way they relate to their own children, leading to the transmission of tendencies toward anxiety, depression, and other conditions.

What is the evidence that childhood abuse can lead to intergenerational trauma?

One example comes from the Nurses’ Health Study, a large-scale, long-term research project exploring risk factors for chronic disease in women. In this study, the children of women who’d experienced physical, sexual, or verbal abuse as children were 1.7 times more likely to experience depression, and 2.5 times more likely to develop chronic depression, than children whose mothers had not experienced such abuse. In a study such as this, it is unclear whether epigenetic changes or, by contrast, parenting style, might have contributed to the effect.

What is collective trauma?

Collective trauma, also known as historical or racial trauma, is the idea that generations of trauma experienced by a large group of people—such as slavery, institutional racism, or colonial exploitation—can broadly influence descendants. This shared experience, the theory suggests, makes members of future generations more prone to conditions like anxiety, depression, or insomnia.
Some psychologists suggest that living through a historical trauma or being raised by someone who did, heightens an individual’s fight-flight-or-freeze response, leading them to rush into that mode of heightened stress at what others might experience as relatively low-threat situations