57. Plomin, R., Petrill, S.A., & Cutting, A.L. (1996). What genetic research on intelligence tells us about the environment. Journal of Biosocial Science, 28, 587-606.

Two of the most important discoveries about the role of nurture in the development of intelligence have emerged from genetic research during the past decade. The first is the importance of non-shared environment--environmental influences that make children growing up in the family different from one another. Often it has been assumed that the key environmental influences on children's development are shared by children growing up in the same family, yet to the extent that these influences are shared by siblings, they cannot account for the differences observed in siblings' IQ. There is a need to identify the environmental factors that make two children growing up in the same family so different from one another. A second significant discovery is that widely used measures of the environment show significant genetic influence.