Eugenicists studied twins to explore genetic and environmental influences on human behavior. Twins, some raised separate from one another, were tested intellectually and measured physically. Eugenicists were looking to prove that heredity determines everything about an individual. They examined fingerprints, hair and eye color, temperament, memory, measured every body part, and even asked subjects how they liked their eggs and steak prepared.

The Archive includes several images from twin studies performed by Otmar Freiherr von Verschuer at the Institute of Hereditary Biology and Race Biology at the University of Frankfurt. These studies were horrifically taken to an extreme by the Nazis in More >