Her father C. Liebrecht was a teacher at the Israelitische Gemeindeschule Gleiwitz, a "Gymnasium" in Upper Silesia, with a PhD in mathematics and natural sciences at the University of Breslau.
"[5] Stern had read and critiqued a paper on the basis for crossing-over by Richard Goldschmidt, the 45-year-old director of the Kaiser Wilhelm Institute for Biology.
Six months later Goldschmidt returned the critique to Stern without comment, called him into his office and offered him a post-graduate fellowship financed by the Rockefeller University at Columbia University, N.Y. to study genetics in Thomas Hunt Morgan's lab, the famous "Fly Room", so-named for the fruit fly Drosophila, the subject of genetic research for Morgan.
[6] After his fellowship, Stern returned to his alma mater, the University of Berlin, where he stayed for six very productive years from 1926 to 1932 as an investigator until he became a professor in 1928.
He was in the company of geneticists Thomas Morgan, Alfred Henry Sturtevant, Theodosius Dobzhansky, Calvin Bridges, Rollins Adams Emerson, C.D.
In 1931, Stern was the first to demonstrate crossover of homologous chromosomes in Drosophila melanogaster, only weeks after Barbara McClintock and Harriet Creighton had done so in maize (corn).
After World War II had begun, Stern fully entered the field of human genetics, supervising his first graduate student seminar in 1939.
[11] Stern's seminar was a response to the eugenic idea of racial hygiene, so prominent in Europe and the U.S. at that time, which had made it impossible for him to continue to live in Germany.
During World War II, he led research for the American government on low-dose radiation safety, building on work he had started in Berlin.
The first edition of Stern's pioneering textbook The Principles of Human Genetics was published in 1949, which he said in an autobiographical sketch from 1974 he wrote to feed the needs of premedical students.
Both his teaching and his textbook were instrumental in re-founding human genetics on a non-racist basis, in sharp contrast with pre-war German and American traditions in the subject.
Notably, Stern made the effort to translate his human genetics textbook into German, which became the first publication in his mother tongue after a 22-year hiatus of silence, and was published in 1955.