Intelligences and Genetics
By an interesting coincidence, the definition of genes, and the measurement of intelligence, both entered human civilization at about the same time. In the first decade of the 20th century, British scientist William Bateson first developed the science of genetics and the notion of a gene; and at the same time, the French psychologist and educator Alfred Binet devised the first psychological tests of intelligence.
Dating back almost to that time, scientists and other commentators have speculated about the genetics of intelligence. This speculation has taken two forms: 1) To what extent is our intelligence inherited from our parents/grandparents? 2) Can we specify the gene(s) that are responsible for/mediate our psychometric intelligence?
Experts differ greatly on the question of the heritability of intelligence. In my own work, I have always assumed that each intelligence has a heritable component but we are far from knowing the extent of heritability of each of the several intelligences.
As this article indicates, there have been many claims to have discovered the gene, or the small set of genes, that determine our psychometric intelligence. The study, emanating from several of the leading scholars in the field, sounds a skeptical note. Based on 10,000 subjects examined in three independent studies, the scholars document their failure to find a significantly positive connection between candidate genes and IQ.
Of course, many conclusions can be drawn from this negative result. I am sure that many scientists, including the authors of this report, will continue to look; and eventually, psychometric intelligence, like almost every other human trait, will turn out both to be heritable and to be linked to certain genes. My own view is that we are more likely to find the genetic bases for various components of the several intelligences; and that the extent to which, and the ways in which, those genetic potentials are expressed will depend heavily on the norms and models in the ambient culture.
To read the study in its entirety click here.