Goddard's research and argument
In its day, The Kallikak Family was a tremendous hit and went through multiple printings. It helped propel Goddard to the status of one of the nation's top experts in using psychology in policy, and along with the work of Charles B. Davenport and Madison Grant is considered one of the canonical works of early 20th century American eugenics.
In recent years, its methodology and conclusions have been standard examples of the problems with early eugenics and heredity research. Though Goddard was considered a true scientist in his day — he was the first to bring Alfred Binet's IQ test to the United States and to translate it into English — his work is now relegated to the same realm of pseudoscience and chicanery as that of the other eugenicists of his era. The majority of Goddard's data was collected by his assistants, upper-class girls from nearby colleges, who would wander into the slums of the "bad" side of the Kallikak family, and spend only a moment before pronouncing a member "feeble-minded."
It has also been argued that, if anything was going along family lines in the Kallikak family, it was wealth or poverty. Malnutrition, for example, goes hand in hand with poverty, and hand in hand with families. If the father of a family cannot afford decent food, then the children will not have it either. Goddard's peer, Davenport, even identified various forms of diseases now known to be caused by diet deficiencies as being hereditary for the same reason: the failure to realize that shared living situations often can make a great many things travel along family lines which have nothing to do with genetic information.
Another recent perspective has been offered that the Kallikaks almost certainly had undiagnosed Fetal alcohol syndrome (FASD).
The paleontologist and popular science writer Stephen Jay Gould also alleged that Goddard — or someone working with him — had retouched the photographs used in his book in order to make the "bad" Kallikaks appear more menacing. In older editions of the books, Gould said, it has become clearly evident that someone has drawn in darker, crazier looking eyes and menacing faces on the children and adults in the pictures. Gould argues that photographic reproduction in books was still then a very new art, and that audiences would not have been as clued into photographic retouching, even on such a crude level.
The psychologist R. E. Fancher, however, has claimed that retouching of faces of the sort which is apparent in Goddard's work was a common procedure at the time, in order to avoid a "washed out" look which was common to early photographic printing methods (poor halftones). Furthermore, Fancher argued, malicious editing on Goddard's part would take away from one of his primary claims: that only a trained eye can spot the moron in the crowd.
The overall effect of The Kallikak Family was to temporarily increase funding to institutions such as Goddard's, but these were not seen to be worthwhile solutions of the problem of "feeble-mindedness" (much less "rogue" "feeble-mindedness" — the threat of idiocy as a recessive trait), and more stringent methods, such as compulsory sterilization of the mentally retarded, were undertaken.
The term "Kallikak" became, along with "Jukes" and "Nams" (other case studies of similar natures), a cultural shorthand for the rural poor in the South and Northeast United States.

See also

Henry H. Goddard, The Kallikak Family: A Study in the Heredity of Feeble-Mindedness, New York: Macmillan, 1912.
Stephen Jay Gould, The Mismeasure of Man, Norton: New York, 1996, revised edn.
R. E. Fancher, "Henry Goddard and the Kallikak family photographs," American Psychologist, 42 (1987), 585-590.
J. David Smith, Minds Made Feeble : The Myth and Legacy of the Kallikaks, Rockville, MD : Aspen, 1985 ISBN 0-87189-093-3