One of the things we have learned in trauma work is that unresolved trauma is often passed down from one generation to the next. The most widely studied example of this has been in Holocaust survivors (especially those who survived the concentration camps) and their children (and grandchildren). [This brief article by Limmud Oz, from a 2006 conference, offers a quick overview of the work with Holocaust survivors.]
There are multiple mechanisms at play in transgenerational trauma (also sometimes called intergenerational trauma), including epigenetics, intersubjective experience with caregivers, interpersonal experience with caregivers, family culture and beliefs, and sometimes abuse or neglect, among others.
This lecture is by Jacek Dębiec, given during the 15th Kraków Methodological Conference - The Emotional Brain: From the Humanities to Neuroscience and Back Again. The main organizer of the conference was Copernicus Center for Interdisciplinary Studies.
Towards a neurobiological model of a transgenerational transfer of traumatic experience