what does iq tell us?


There has been a disturbingly popular belief over the years that intelligence is genetic. Smart people have smart kids. Stupid people have stupid kids. It’s observable and seems to be backed up by academics claiming that around 70% of our intelligence is genetically inherited. All the smart people who go to good schools from well-established families fall over themselves to agree – they paid for top class education to make the most of their top class abilities. Why waste money educating people with no real prospects?

Professor Robert Plomin, who has been advising the UK government in relation to education policy, and who is confident in his figure of 70%, tells us:

Most of what is currently known about the genetics of intelligence comes from twin and adoption studies, which have documented significant and substantial genetic influence.

I have two serious issues with using adoption and twin studies to guide us in any nature/nurture discussion:

  1. Perhaps the most crucial stage of development for any person is the nine months spent in the womb of their mother. In terms of nutrition and chemical trauma, twins will generally have similar experiences in this key developmental stage.
  2. Adoption studies in developed countries can only tell us how children homed with families vetted to ensure they can provide sufficient levels of material and emotional support will fare. No child would be placed with a family who couldn’t or wouldn’t ensure reasonable nutrition and access to education.

The 40-year Barbados Nutrition Study concluded that:

Moderate-to-severe malnutrition during infancy is associated with a significantly elevated incidence of impaired IQ in adulthood, even when physical growth is completely rehabilitated. An episode of malnutrition during the first year of life carries risk for significant lifelong functional morbidity.

In my opinion, IQ tests generally can only give us a vague measure of the opportunities people have had in life. These opportunities include a pleasant incubation in their mother’s womb, decent levels of nutrition throughout childhood, access to reasonable educational facilities and, for most, supportive and encouraging families. However, even taking all this into consideration, high IQs cannot be worshipped as a tool to cure all ills, but should be regarded to be of use alongside a whole range of other competencies that make any life of value.

[Anyone interested in further reading on this subject might want to check out this article.]