How Nature and Nurture Contribute to Intergenerational Trauma

A friend of mine recently asked, “Do you believe in intergenerational trauma?” My affirmative answer
spurred his curiosity: “But how does someone’s, say, war trauma that happened to them get passed to another generation?” More wondering emanated from the passenger seat about next generations getting vicarious trauma from hearing war stories. Then something about perhaps genes can be altered by trauma to encourage hypervigilance and aggressive reactivity in offspring as a preemptive strike against potential trauma of their own.

Both of my compadre’s ideas are viable possibilities, vicarious trauma being a well-researched topic, and trauma-induced genetic alteration is an emerging area of research interest. Evidence does exist (e.g., Chou et al., 2024) that environmental stimuli “can be written into heritable material…and persist to the next generation,” which primes the new generation for how to respond to traumatically stressful environmental stimuli, sort of like my friend hypothesized.

In any event, it is not that someone’s specific traumatic experience gets passed down, like each succeeding generation has flashbacks of their great-great-grandfather’s World War I incidents. Rather, like most things in psychology, there is a complex interplay of nature and nurture lending itself to generational perpetuation of the pervasive chaos of one person’s long-ago trauma.

Borderline personality disorder as intergenerational trauma

My favorite illustration of this is borderline personality disorder (BPD). The foundation of BPD tends to be abandonment/rejection by an early attachment figure(s). As the person ages, their lives revolve around fear of abandonment/rejection. Numerous maladaptive behaviors/defenses follow, like reactive rage, self-destructive activities, identity disturbances (such as chameleonizing to various people/groups, for who would want to reject one of their own?), attention-seeking, and a push-pull attachment style.

Further, people with BPD have genetic/brain anomalies (e.g., Ansari et al., 2023) including amygdalar hypersensitivity, low serotonin, and an underperforming prefrontal cortex that contribute to activating anxiety, poor impulse control, anger, and aggression. Researchers (e.g., Plunk & Richards, 2020) have shown that how genes are expressed, or turned on and off, can be influenced by environmental factors in a process called DNA methylation. This can influence gene expression in next generations, known as transgenerational epigenetic inheritance. BPD researchers (e.g., Dawidowski et al., 2025) are finding increasing evidence that this plays a large role in the development of BPD.

An illustrative case

The story of Eddie and Jeanine, and their following generations, illustrates how this comes together for intergenerational trauma. It is based on a real example, and all names and some details have been changed:
Three generations ago, Eddie doted over Jeanine. They married quickly, bought a house, and had two kids, making for increased bills. Thus, Eddie worked more and would spend time doting over the kids when home and less over Jeanine, but still was a good husband. Jeanine began wondering if Eddie was working more shifts to avoid her. After all, he seemed more interested in the kids, and their romance declined.

Never financially responsible, Jeanine suggested they open another credit card to cut back on Eddie’s work schedule; Eddie explained credit cards need to be paid off in a timely fashion, so it wouldn’t make a difference. “Clearly, this is an excuse,” thought Jeanine. She became cold toward Eddie, even aggressive if he came home later than usual. “Is he having an affair?” she thought. She wasn’t going to be ignored. Jeanine began getting together more frequently with high-school friends and gave her version of the story. One friend, Jeff, saw her as a damsel in distress, and one thing led to another.

Jeanine idealized him as her “savior” from a lousy, “cheating” husband and left her family to live with him. The kids, ages 2 and 3 at the time, saw her periodically and were confused about why she left home, rendering the rise of their own feelings of abandonment. Eddie had the kids most of the time, but with shared custody, they sometimes stayed with Jeanine. There, they witnessed domestic violence and Jeanine kicking Jeff out of his own house if he didn’t meet her expectations, an echo of her family-of-origin dynamics.

Little Penelope always identified with Jeanine in her malleable years, given she was the female attachment figure. At Jeff’s house, she didn’t like a lot of what she saw, but Penelope somehow felt this was how one was supposed to relate to others. With age, her own fears of abandonment heightened; if one’s mother would simply take off, anyone could. She was always looking for evidence that someone was about to reject her. She’d push people away in a preemptive strike if she suspected pending rejection, a common BPD defense (i.e., “I pushed them away; they didn’t reject me!”). Eventually she would realize her error and pull them back in, but also let them know how disappointed she was for “making” her feel rejected.

As Penelope began dating, the dynamic matured. She would even be physically aggressive with some guys, raging at them if she saw them socializing with another girl. Other times she would self-destruct, cutting herself in punishment for feeling she must not be good enough if, as she perceived it, a boyfriend needed any girl’s attention but hers.

Penelope’s early attachment trauma began taking its toll. She demanded attention and guarantees of nonrejection. She would sexually saturate any guy she dated, because what guy would want to get rid of that? Her only demand was that they spend every second together. The guys quickly felt emotionally suffocated; the relationships became tumultuous and would abruptly end. She became pregnant and married the child’s father. Soon, little Bobby was immersed in watching one or the other parent leave for periods and not see them. Later, Penelope was sometimes passed out drunk in the mornings, and thus, Bobby was often absent from school. This led to DCF investigations and a series of removals over the years.

Not surprisingly, Bobby found it difficult to relate to others due to the attachment trauma, influencing his gene expression and evolution of BPD, and the cycle continued.

Generations of inherited proclivities coupled with exposure to traumatic events that shape interpersonal behaviors and activate genetic traits create a perfect storm that, in some cases, eternally perpetuates the intergenerational trauma.

Disclaimer: The material provided in this post is for informational purposes only and is not intended to diagnose, treat, or prevent any illness in readers or people they know. The information should not replace personalized care or intervention from an individual’s provider or formal supervision if you’re a practitioner or student.

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