Nancy L. Segal1
Genetically unrelated same age siblings, reared together from early infancy, offer a novel research design for studying genetic and environmental influences on behavior. An initial report on IQ findings from this ongoing project appeared in the Journal of Educational Psychology (1997). Participants ranged in age from 4-26 years. The IQ correlation for 21 pairs was .17, the verbal IQ correlation was -.01, the performance IQ correlation was .29, and the mean within-pair IQ difference was 15.38 (SD= 11.45). Interestingly, an increase in performance IQ similarity with age was observed. Additional data have now been collected for 56 pairs, who range in age from 4 - 56 years. IQ data will be reported for the larger sample, and future plans for this ongoing study will be described.
Address: 714-278-2142, 714-278-7134, nsegal@fullerton.edu
1Psychology Department, California State University, Fullerton, California 92834. 2Supported by the National Science Foundation (SBR-9712875) and a faculty research award from California State University, Fullerton.