Around 1900 many people feared that the poor, the mentally disabled and the criminals would have so many children that society to collapse. This led to some scientists and politicians advocating eugenics, i.e. the idea that certain groups of society should be prohibited from having children. In the 1920s particularly in the United States, Germany, Sweden and Denmark, politicians enacted laws which allowed compulsory sterilization of the mentally ill and the mentally disabled. The eugenic laws were gradually abrogated after World War II where the gas chambers of Nazi-Germany showed how dangerous the idea of worthy versus unworthy human beings was.
Eugenics was based scientifically on the genetics of Gregor Mendel and Charles Darwin’s theory on natural selection which the eugenicists wanted to combine with a political selection of who was considered suited to have children and thereby pass on their genes.
In the period from 1859 to 1920, one of the relatively few supporters of eugenics in Denmark was the dentist and nutritionist Alfred Bramsen while the well-renowned geneticist Wilhelm Johannsen strongly opposed the idea.
Bramsen, Alfred: “Natur og Opdragelse – Betragtninger i Anledning af Darwinismens Jubilæum”, Det Ny Aarhundrede, vol. 6, pp. 823-832