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

292 PROMOTING POTENTIAL

possibility of treating psychological conditions in analogous ways, that is,
by assuming that diff er ent environments have diff ering eff ects on individ-
uals with diff er ent genes. Th is has been called “diff erential susceptibility”
and has been speculated to apply to vari ous conditions, such as alcoholism,
smoking addiction, and a range of childhood behavioral prob lems.
However, the theoretical naiveté of ignoring the many pathway inter-
actions (as I described in chapters 4 and 5) has been pointed out.^1 Failure
to account for these interactions prob ably explains why results have been
inconsistent. As Irene Pappa and colleagues point out in their review,
pinning discrete functions, or functional variation, on diff er ent alleles
has been impossible. Studies have given rise to “an overall lack of consistent
fi ndings” with “no certainty that these [allelic] diff erences result in bio-
logical, functional eff ects.”^2
Further diffi culties have been encountered when the disease condi-
tions refl ect not one, but the combined consequences of multiples of de-
viant genes. However, it is such a polygeneic model of diff er ent sums of
more or less “good” genes that has been applied to the normal ranges of
complex cognitive traits like human intelligence. Th e hope has been to
fi nd analogous environmental treatments for helping those with poor
gene combinations.
Th is is what seems to be proposed by, for example, Kathryn Asbury
and Robert Plomin in their book, G Is for Genes. Th e description gets
rather vague, but it seems that each child, aft er DNA sequencing, will go
to school with a learning chip as “ge ne tic predictor” of learning “strengths
and weaknesses.” Teachers will then devise learning programs to suit,
thus ensuring that each pupil gets the best pos si ble treatment. Indeed,
in an interview in the Guardian newspaper, Plomin says, “It’s wholly
accepted that preventative medicine is the way to go.... Why not pre-
ventative education?”^3
Other inspiration has come from the possibilities of direct gene therapy
or ge ne tic engineering, also arising from DNA sequencing. Th is involves
structurally “correcting” a gene, by altering a DNA sequence, to prevent
or treat a disease. Several pos si ble techniques are currently being per-
fected for achieving this. For example, it might be pos si ble to knock out
a mutated gene; or it could be replaced with a healthy copy. A new tech-
nique (CRISPR, short for “clustered regularly interspaced short palin-

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