Some new/old findings about IQ

A paper titled "Top 10 Replicated Findings From Behavioral Genetics" has just come out with Robert Plomin as lead author.  The finding of the paper is an embarrassment to most psychologists.  We now know that most findings from psychological research are NOT replicable.  They are a flash in the pan with no generalizability.  They tell us nothing. So the fact that findings about the influence of genetics on behavior ARE replicable makes them stand out from other research.  It is putting it a little to strongly to say that it is the only sort of psychological research that it worth bothering with, but it gets close to that. I say here why I gave up on survey research after 20 years of doing it.

I have always noted that the heritability of IQ is by far the best replicated finding in psychology but Plomin shows that other effects of genetics on behaviour are highy replicable too.  Leftists hate all mention of genetics so on that issue, as on many others, they are on the wrong side of history.  And how ironic that is precisely the most well substantiated findings in psychology that are too politically incorrect for general mention.

So why are studies in the genetics of behaviour so robust?  Plomin suggests five sensible reasons but let me give a more impressionist reason:  It is because genetic effects on  behaviour are REAL.  There really is something going on there.  And, as Plomin's other findings show, what is going on is that genetics have a strong and pervasive effect on ALL behaviour.  As Plomin points out, even family environment is not an influence in its own right.  It too is affected by genetics.  I am reminded of something Hans Eysenck said to me around a quarter of a century ago:  "It's ALL genetics".  Already in his time, he had seen how pervasive genetic influences were.

My days as an active psychological researcher are long gone and I read very little in the psychological research literature these days.  I have however kept a watching brief on research on IQ.  So I was well aware of one of Plomin's more surprising findings:  The influence of IQ GROWS as the person grows up.  IQ is only a small influence of behaviour in early childhood but a large influence on the same person's behaviour in adulthood.  The genetic infuence in fact seems to keep growing until about age 30.  That can be seen as rather counterintuitive.  One would think that a small child had ONLY genetic influences to guide his behaviours but as he grew up he would come under all sorts of additional influences on his behaviour.

Plomin explores some possible reasons behind that finding but I think he misses the obvious:  A child is very heavily regulated whilst growing up.  He is pushed in all sorts of directions by parents, teachers and others.  It is only in adulthood that he is reasonably free to "be himself".  And that is exactly what happens.  He throws off most of his environmental influences and behaves in a way that feels good or right to himself.

Posted by John J. Ray (M.A.; Ph.D.).