Fritz Lenz was born in Pflugrade in Pomerania. He spent his childhood in Stettin. During the First World War, he was responsible for hygiene in the Puchheim prison camp. He married his first wife Emmy Weitz in 1915. They had three sons. After studying medicine in Berlin, he published his first standard work on ‘racial theory’ in 1921. Two years later, he became the first professor of ‘racial hygiene’ in Germany. As such, he was involved in the ‘Law for the Prevention of Hereditarily Diseased Offspring’ and in consultations on a ‘Euthanasia Law’ during the National Socialist era.
In 1929, he married his second wife Klara von Borries. Lenz had two more children with her. Two of his sons became professors of mathematics and physics. A third son became a human geneticist.
After 1940, Lenz increasingly withdrew and moved to Münster in 1944. From 1945, he worked as a professor of human genetics at the University of Göttingen. In 1949, he was denazified as ‘exonerated’ and retired in 1955. Until his death in Göttingen in 1976, he was convinced of inequality within the ‘human races’.
