Plomin & Craig, 2001: The genetics of intelligence (g) - Takin' it to the Brits

This was one of my favorite letters to write.  I was passing some time in the "library" at my job and there happened to be a British Journal of Psychiatry sitting on the table.  I pick it up and, lo and behold, there is a study purporting to show a genetic link for g (a fanciful version of I.Q).  I'm sure the authors didn't intend it, but this kind of stuff is really not much different than old time eugenics.  I decided to challenge the assertions and sent the BJP a letter.  To my surprise, they printed it with a reply from the authors.  I was quite amused that they changed my "randomization" to "randomisation" for the Brit-friendly audience.  I also didn't know that they call raisins "sultanas" there.  Rather than post the letter and the reply from the authors (which is linked above), I'll just make a few points:

First, I referred to an excellent book on the subject of eugenics, called The Mismeasure of Man by Stephen Jay Gould (rest in peace, sir).  To this Plomin and Craig remarked:

Although g may be controversial in the media, it is no longer controversial among scientists or science journalists.

Okay, first of all,  I will put Stephen Jay Gould's scientific credentials above any of the "science journalists" that they can name who support g.  Secondly, The book The Bell Curve by Hernstein and Murray is more than a little controversial, effectively claiming that white people are smarter than black people based on g.  This is why I care about these studies and write letters to the editors of scientific journals.  When you start claiming that various things are "genetic," you are changing people's perception of things.  If you say something is genetic, you give the perception that is simply an organic fact, for which little can be done, whether that is intelligence, antisocial behavior, mental illness, alcoholism, etc., it changes how people are treated, whether they are institutionalized, incarcerated, etc. This is the world of eugenics.  Now, of course, you might argue: "Facts are facts" in science, and the truth is what is important.  This is exactly my point.  Stop publishing bad studies that imply a genetic link that doesn't really exist, because it perpetuates certain biases and prejudices that have far-reaching implications and might not even be true.  Plomin and Craig use the usual rationalization (or "rationalisation" as the case may be) to justify their study:

The evidence for a substantial genetic basis to g is so overwhelming that there is no longer any need for studies that merely demonstrate yet again the heritability of g.

Okay, first of all, "heritability" and "genetic basis" are two different apples.  It might be nice to believe that anything that runs in families is genetic, but since NO GENE HAS BEEN CONSISTENTLY SHOWN TO CORRESPOND TO ANY MENTAL ILLNESS OR PERSONALITY TRAIT TO DATE, call me underwhelmed.  Secondly, this claim does not add to the credibility of your study.  I challenged the authors to create a control for the study and they basically say "too late," but then their reply gets kind of interesting: 

The in-progress research described in our review has led to a genome scan using nearly 2000 markers in which we find no associations with g that cleanly replicate in two case—control samples

So, unbeknownst to me, they actually had attempted to replicate their initial findings and could not.  That, of course, should be the end of it.  I win... But wait, they aren't going to give up that easily.

Although the many hurdles that we set for acceptance of a quantitative trait locus association may have been too high, it is important to be conservative in light of reports of associations with complex traits that do not replicate (Plomin et al, 2002b). None the less, we are following up several promising leads, as well as applying new approaches that capitalise on methodological and substantive advances from the Human Genome Project.

Okay guys, it has been eleven years.  How many "g" genes have you located with your "promising leads"? I'm guessing ZERO.    This is the benefit of challenging these studies.  You then have some history to work with.   This kind of kibitzing may seem pedantic to some, but as I note above, there are some important issues that come to the forefront because of decades of  research that is simply producing false positive results.