For good and various reasons, though not compelling ones, American behavioral scientists have long shown a remarkable indifference to the possible role of heredity in the etiology of behavioral disorders. The reasons included: a healthy skepticism regarding the validity and reliability of assessing traditionally defined diagnostic categories, such as schizophrenia, manic-depressive psychosis, psychoneurosis, psychopathy, and others; the association offallacious, hereditary theories with the political ideology of the Nazis; the fact that genetic research has sometimes been linked to the suppression of black people; the repugnance to Americans of any theory that implied a genetic determination of behavior, even in part, in that it threatened to delimit our concept of personal freedom as well as our subjective or collective consciousness of such freedom; the fact that so-called genetic research has often been cavalier in its disregard of basic, accepted methodological practices, such as the use of a control group, or making assessments while blmd with respect to the relationship between a subject and the index case in a given study; the popular but mistaken belief that if a disorder had a genetic basis, it was ipso facto untreatable; the absorption of psychologist in psychodynamic explanations of psychopathology and in principles of learning left little room for an ego-alien notion such as genetics in their conceptualization of behavioral disorder; and the fact that none of the behavioral disorders followed any clear Mendelian distribution.