The country was not ready
Orphanage populations grew during the Depression as desperate parents could not feed their children and made the harrowing decision to give them up. Faced with many children with carious family lives, researchers at orphanages in Iowa performed several studies to determine the role of environment on the intelligence of children. Their findings were overwhelmingly clear. A loving and supportive environment gave a big boost to intelligence. Children considered seriously impaired improved greatly when their environment changed for the better. However, the prevailing view was that IQ was set at birth and would never change, leading many scientists to support eugenics. These Iowa researchers were mocked and ridiculed. It was not until the old stalwarts of this theory died in the 50's and 60's and more studies were done, that these researchers were finally believed. Old ideas die hard, but some need to die, especially in light of new evidence.