(p. C4) Hardly any subject in science has been so politically fraught as the heritability of intelligence. For more than a century, since Francis Galton first started speculating about the similarities of twins, nature-nurture was a war with a stalemated front and intelligence was its Verdun–the most hotly contested and costly battle.
So would it not be rather wonderful if a scientific discovery came along that called a truce and calmed all the fury? I think this is about to happen. Call it the Goldilocks theory of intelligence: not too genetic, not too environmental–and proving that intelligence is impossible to meddle with, genetically.
The immediate cause of this optimism is a recent paper in Molecular Psychiatry, which confirms that genes account for about half of the difference in IQ between any two people in a modern society, but that the relevant genes are very numerous and the effect of each is very small.
The paper refereed to in the quote from Ridley’s commentary is:
Davies, G., A. Tenesa, A. Payton, J. Yang, S. E. Harris, D. Liewald, X. Ke, S. Le Hellard, A. Christoforou, M. Luciano, K. McGhee, L. Lopez, A. J. Gow, J. Corley, P. Redmond, H. C. Fox, P. Haggarty, L. J. Whalley, G. McNeill, M. E. Goddard, T. Espeseth, A. J. Lundervold, I. Reinvang, A. Pickles, V. M. Steen, W. Ollier, D. J. Porteous, M. Horan, J. M. Starr, N. Pendleton, P. M. Visscher, and I. J. Deary. “Genome-Wide Association Studies Establish That Human Intelligence Is Highly Heritable and Polygenic.” Molecular Psychiatry 16, no. 10 (October 2011): 996-1005.