The American Rockefeller Foundation funded numerous international researchers to visit and work at Rüdin's psychiatric genetics department, even as late as 1939. These included Eliot Slater and Erik Stromgren, considered the founding fathers of psychiatric genetics in Britain and Scandinavia respectively, as well as Franz Josef Kallmann who became a leading figure in twins research in the US after emigrating in 1936. Kallmann had claimed in 1935 that 'minor anomalies' in otherwise unaffected relatives of schizophrenics should be grounds for compulsory sterilization.