Complex sentence: According to Six, the concept of the film arose from a joke he made with friends and Nazi medical experiments carried out during World War II, such as the actions of Josef Mengele at Auschwitz concentration camp.
Split into simpler sentences: According to Six, the concept of the film arose from a joke he made with friends. Six also stated that inspiration for the film came from Nazi medical experiments carried out during World War II, such as the actions of Josef Mengele at Auschwitz concentration camp.