Genes, Brains, and Human Potential The Science and Ideology of Intelligence

50 PRETEND GENES

The “Environment”
No one ignores the role of the environment. As with genes, though, the
environment is conceived in a special, idealistic, way to render the behav-
ioral ge ne tic model testable. We are asked to assume that, in the creation
of individual diff erences, the environment merely provides resources for,
stimulates, obstructs, or other wise attenuates what is essentially in the
genes. It is usually presented in terms of vague “ factors” contributing in-
de pen dently of one another, again to result in a bell- shaped curve to make
the statistics easy.
Th is is the idea behind common expressions like “Th e genes deter-
mine potential while the environment determines how much of it is at-
tained.” Th is is what is meant when behavioral ge ne ticists acknowledge
the role of gene- environment interactions. Attempted disclaimers like
“Most things are down to both nature and nurture,” or “Genes and
environments work together,” are common. But we are left in no doubt
over what is really in control. In fact, when comparing twins, the envi-
ronment that is said to var y is not identifi ed or mea sured at all; it is treated
as the components of variation left over from the correlations between
the twins.

All this has been suspected for de cades. Th e leading ge ne ticist Sewall

Wright explained in the 1930s that interaction among gene products is

ubiquitous: “Our knowledge of biochemistry and physiology strongly

suggests that interaction among gene products is ubiquitous.” In a more

recent review, Hongxia Shao and colleagues show how gene products

and other cell components “interact in complex ways” that are “perva-

sive” in the cell.^10

But the behavioral ge ne ticists of IQ do not ignore interaction eff ects in

their models out of naiveté. Th ey do so out of pragmatism. My worry is

that pragmatism further opens science to ideology— that is, obfuscating

and omitting details that might spoil a story already derived from what

is supposedly socially obvious.

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