At the turn of the 20th century, studies of a family known in the literature as the Kallikaks were used to document the hereditary nature of mental retardation, poverty, and antisocial behavior. This family was said to authenticate eugenic theory, which states that heritable characteristics carried by individuals on "independent unit characters are unalterable determinants of behavior and performance. A review of the original Kallikak data, however, suggests that in utero exposure to alcohol rather than heredity contributed significantly to the transgenerational learning failure seen throughout the Kallikak pedigree. However, eugenic theory was so thoroughly accepted that the promotion and acceptance of "hereditary feeblemindedness" as the principal cause of the developmental problems in the affected offspring smothered the research efforts on in utero effects of alcohol until long after the eugenic concepts were abandoned later in the century.