The Refrigerator mother theory, also known as Bettelheim's theory of autism, is a controversial psychological theory that the cause of autism is a lack of maternal (figurative) warmth. Evidence against the refrigerator mother theory began in the late 1970s, with twin studies suggesting a genetic etiology, as well as various environmental factors. Modern research generally agrees that there is a largely epigenetic etiology of autism spectrum disorders. The terms refrigerator mother and refrigerator parents were coined around 1950 as a label for mothers or fathers of children diagnosed with autism or schizophrenia. When Leo Kanner first identified autism in 1943, he noted the lack of warmth among the parents of autistic children. Parents, particularly mothers, were often blamed for their children's atypical behavior, which included rigid rituals, speech difficulty, and self-isolation. Origins of theory In his 1943 paper that first identified autism, Leo Kanner called attention to what appeared to him as a lack of warmth among the fathers and mothers of autistic children. In a 1949 paper, Kanner suggested autism may be related to a "genuine lack of maternal warmth", noted that fathers rarely stepped down to indulge in children's play, and observed that children were exposed from "the beginning to parental coldness, obsessiveness, and a mechanical type of attention to material needs only.... They were left neatly in refrigerators which did not defrost. Their withdrawal seems to be an act of turning away from such a situation to seek comfort in solitude." In a 1960 interview, Kanner bluntly described parents of autistic children as "just happening to defrost enough to produce a child." Bruno Bettelheim at the University of Chicago was instrumental in facilitating its widespread acceptance both by the public and the medical establishment. Bettelheim was hired in 1944 to be the director of the Orthogenic School for Troubled Children at the University of Chicago as a residential treatment milieu for such children, who he felt would benefit from a "parentectomy". This marked the apex of autism viewed as a disorder of parenting. Bettelheim later expounded his theories about autism in his 1967 book "Empty Fortress: Infantile Autism and the Birth of the Self". In it, he compared autism to being a prisoner in a concentration camp: In the 1950s and 1960s, in the absence of any biomedical explanation of autism's cause after the telltale symptoms were first described by scientists, Bettelheim, as well as some psychoanalysts,