Natan P F Kellermann, PhD was born in Sweden but moved to Israel in 1980. He was a practitioner and trainer of psychodrama and sociodrama and investigated what is helpful in these approaches. He worked in Amcha: an Israeli treatment center for Holocaust survivors and their families, as the chief clinical psychologist in Jerusalem between 1996-2000, executive director between 2001-2004, project development director until the end of 2011, a member of the board of directors until the end of 2016 and director of research from 2017 until mid 2018. For more than ten years, he lectured on Holocaust trauma at the International School for Holocaust Studies in Yad Vashem. His focus of study is the transgenerational transmission of trauma.