Transgenerational trauma is trauma that is transferred from the first generation of trauma survivors to the second and further generations of offspring of the survivors via complex post-traumatic stress disorder mechanisms.
Soon after descriptions of concentration camp syndrome (also known as survivor syndrome) appeared, clinicians observed in 1966 that large numbers of children of Holocaust survivors were seeking treatment in clinics in Canada. The grandchildren of Holocaust survivors were overrepresented by 300% among the referrals to a child psychiatry clinic in comparison with their representation in the general population.
The phenomenon of children of traumatized parents being affected directly or indirectly by their parents’ post-traumatic symptoms has been described by some authors as secondary traumatisation (in reference to the second generation). To include the third generation, as well, the term intergenerational transmission of trauma was introduced. Building upon the clinical observations by Selma Fraiberg, child trauma researchers such as Byron Egeland, Inge Bretherton, and Daniel Schechter have empirically identified psychological mechanisms that favor intergenerational transmission, including dissociation in the context of attachment, and "communication" of prior traumatic experience as an effect of parental efforts to maintain self-regulation in the context of post-traumatic stress disorder and related alterations in social cognitive processes.
Both survivors and immediate witnesses of traumatic events in family history have traditionally been treated by family therapists. The first-generation experiences of combat veterans, hostages, prisoners of war, and the civil population who was victimized at the hands of war criminals from genocidal organizations such as the German Nazi Party, Italian Fascist party, and similar organizations and their (para-)military arms, have been dealt with within the confines of political arena and international law, however the descendants of both immediate witnesses and victims of genocide, colonial suppression, slavery, political totalitarian control, clerical abuse in religious organizations, and many survivors of terrorism had to deal with the victimization symptoms themselves, without the transfer of original trauma being recognized and help offered.