Kallikak: A Study of the Heredity of Feeble-Mindedness
Heredity has long been a subject of scientific inquiry, and the concept of feeble-mindedness has long been a topic of debate. In 1912, Henry Herbert Goddard published a study of the heredity of feeble-mindedness, entitled Kallikak. This paper was a landmark study in the history of psychology and has been influential in the development of the study of human intelligence.
In the study, Goddard examined a family which he referred to as the Kallikak family. The family was traced back to an American Revolutionary War soldier, Martin Kallikak, Sr. It was discovered that Martin Kallikak had a relationship with a “feeble-minded” woman, producing a son, Martin Kallikak, Jr., who also had a relationship with a feeble-minded woman. The study traced the family lines of both of these sons, and found that the line of Martin Kallikak, Jr., which included several generations of individuals who were deemed “feeble-minded”, was much more prolific than the line of Martin Kallikak, Sr., which did not have any instances of feeble-mindedness.
Goddard concluded that the “feeble-mindedness” of Martin Kallikak Jr. and his descendants was likely due to their shared genes. He stated that “the facts of heredity are so strong and so persistent that it is difficult to escape the conclusion that the feeble-mindedness of the Kallikak family is due to a single ancestral taint.” This study was influential in the development of the idea that mental illness and intellectual disability is often inherited, and was a key factor in the development of the eugenics movement in the early 20th century.
Goddard, H. H. (1912). Kallikak: A study of the heredity of feeble-mindedness. New York: Macmillan.
Kirby, A. (2005). Making sense of the Kallikak study. Mental Retardation, 43(3), 199–202. doi:10.1352/0047-6765(2005)0432.0.CO;2