Over the past few decades, hundreds of "genetic links" have been "found", largely through genome-wide association studies, in which the researchers look at hundreds of different genetic loci to find 1 or 2 that are more highly correlated in their study group vs. their control group, whether this be for intelligence, schizophrenia, "novelty-seeking", etc. As I've already mentioned, these studies tend to crank out a lot of false positives, which even the scientific community is coming to terms with, as can be seen here. So, since almost all of the hundreds of alleged genetic linkages have not been replicated, we might expect to see a lot of studies in the literature that give negative results, refuting the previous positive results. In actuality, although we occasionally do see that, it is the exception rather than the rule.
We never get a mea culpa for the bogus results of previous studies, some of which made a big splash with front page news in major newspapers when they came out. So they remain reinforced as a truism in the minds of scientists and the general public: "Gene for Schizophrenia Found," "Scientists Show That Intelligence is Genetic," "ADHD is Inherited in Our Genes," etc. You never see the New York Times retract a story 4 years later, when it becomes obvious that the study was a false positive. In fact, by that time, they've put up 5 or 10 more similar headlines for other genetic linkage studies, all of which are also eventually refuted.
Of course, one could argue that it's not the job of major newspapers to keep track of every development in science. That should fall on scientists and scientific journals. If a particular gene is found to have a correlation to a certain disorder or trait in a genome wide association study (GWAS), then someone should be doing a study ON JUST THAT GENETIC LOCI, looking at it specifically.
Interestingly, that is rarely done or, if it is, the studies rarely make it into journals (presumably due to negative results). It just doesn't pay to put out negative studies.
It is much more rewarding to continue cranking out GWAS's, that are almost assuredly going to have a few positive results (false positive, mind you, but that's not their problem). In fairness, I believe this is in part due to the publishing pressure felt by most academics who want to bolster their careers. Putting on your resume that you demonstrated that a previously proposed genetic linkage was a false positive, is far less exciting than saying you found a potential genetic link to IQ.
An interesting aspect of this abundance of GWAS papers, is that it is rarely pointed out that the latest paper, by omission, is refuting all previous linkages. If you do a GWAS and it shows a positive linkage to 2 genetic loci, but doesn't show if for loci from the previous genetic linkage studies, then you have effectively refuted the previous studies, even if you make no mention of it. In other words, one could argue that each GWAS largely just refutes all the previous GWAS's to date, while pointing out a few new POSSIBILITIES for future studies. Sometimes you will get a brief mention in the conclusion of a study that they didn't replicate a previous study's findings, but they certainly don't come out and say that all the other claims of linkage were false positives.
So I am proposing that 20 + years of GWAS studies have clearly demonstrated that there are no genetic linkages to intelligence...
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