Japanese eugenic discourse and institution building contrast sharply with comparable movements elsewhere. As a social-intellectual phenomenon, Anglo- American eugenics considered the Japanese racially inferior to Western peoples; yet eugenic ideals and policies achieved a remarkable popularity in Japan. Most of mainstream Japanese genetics was derived from orthodox Mendelian roots in Germany and (to a lesser degree) the United States. But French-style Lamarckian notions of the inheritability of acquired characters held surprising popularity among enthusiasts of eugenics. Japanese eugenicists could condemn the actions of foreign eugenicists like Charles Davenport in the United States for their efforts to forbid Japanese immigration in the 1920s, yet appeal to these same eugenicists as a source of legitimacy in Japan.
These paradoxes can partly be explained against a background of relative isolation in a period of profound social change. Few Japanese eugenicists had close personal contact with foreign eugenicists, and most of their knowledge was acquired through reading rather than direct exposure. The eugenic ideal of ethnic purity was attractive to a society long accustomed to monoracial self-imagery. The need to defend national independence in an era of high imperialism seemed to require the most up-to-date policies and ideas. And Japan's own acquisition of an overseas empire seemed to demand a population management philosophy ostensibly based on scientific principles. These and other forces supported the implementation of eugenic policies and prescriptions among the Japanese people in the first half of the twentieth century.