(J Intelligence and Family Size: Another Look

Periodically, fears are voiced that the intelligence level of the u.s. population is falling. Historically, this fear has been joined to the belief that fertility is inversely related to intelligence. Evidence for that belief is sparse, and may be an artifact of the failure of researchers to consider completed families. An inverse correlation between measures of intelligence.and number of children in young samples may simply reflect differentials in timing and spacing of births, and not in ultimate family size. Drawing on data from only ever-married and relatively older men in the NBER-Thorndike and Kalamazoo Brothers samples, the authors find no inverse relationship between test scores and number of children. Since ever-marrieds are expected to show the greatest negative relationship, these results are all the more telling. "Intelligence and Family Size: Another Look 1