Two questions will receive special attention in this account, namely the political location of eugenics and the role of genetic science in its development. I will show that moderate eugenic policies had broad political support. For instance, the Scandinavian sterilization laws which were introduced in the 1930s were supported by the Social Democratic Parties, who were partly in position of government. I will argue that the effect of genetic research was to make eugenics more moderate, mainly because the fears and hopes were shown to be exaggerated. Degeneration was much slower than feared at first, if it took place at all, and the expectation of rapid and large effects of eugenic policies on the gene pool likewise proved to be quite unrealistic.