During the 1930s and 1940s institutes in Nazi Germany studied genetics, created genetic registries and researched twins. Nazi scientists also studied blood, and developed theories on the supposed racial specificity of blood types, with the goal of distinguishing an "Aryan" from a Jew by examining their blood. In the 1930s, Josef Mengele, a doctor in the Schutzstaffel (SS), provided human remains that were taken from Auschwitz – blood, limbs and other body parts – to be studied at the institutes.