The New York Times "Sunday Review" section has anointed Richard Friedman its go-to guy for touting behavioral genetics--or "gene-whiz science," as I prefer to call it. In March, Friedman, professor of clinical psychiatry at Weill Cornell Medical College, proclaimed that researchers had discovered a "feel-good gene," which "makes some people inherently less anxious, and more able to forget fearful and unpleasant experiences."
As I pointed out on this blog, Friedman's claim—like virtually all reported linkages of complex human traits and disorders to specific genes (see Further Reading)--is based on flimsy, contradictory evidence. I'm so naïve, or arrogant, that I actually thought my critique might dissuade the Times from further hype of gene-whiz science. Times editors must care more about traffic than accuracy, because they devoted almost the entire front page of yesterday’s "Sunday Review" to Friedman's latest travesty, "Infidelity Lurks in Your Genes."
The core of Friedman's essay is his assertion that some women are "biologically inclined to wander." More specifically, women who carry variants of the gene AVPR1A—which encodes the receptor for the hormone arginine vasopressin--are "much more likely to engage in 'extra-pair bonding,' the scientific euphemism for sexual infidelity."
In support of this claim, Friedman cites a study of Finnish twins and non-twin siblings by a team led by Australian psychologist Brendan Zietsch. The team surveyed the Finnish subjects and found that 9.8 percent of the men and 6.4 percent of the women reported engaging in at least one "extra-pair mating." The researchers found an association between five AVPR1A markers and extra-pair mating in women but not in men.
First, self-reports are notoriously unreliable, but that's not the primary problem with the Zietsch study. The problem becomes apparent toward the end of the paper, when the authors acknowledge that their results "do not directly replicate previous results in humans."
That's an understatement. A 2004 study found no association between AVPR1A and extra-pair mating in either men or women. A 2008 study found an association between one AVPR1A polymorphism, called RS3, and poor pair-bonding in men; Zietsch et al. found no association between RS3 and extra-pair mating in men or women. Many other groups have linked mating behavior to so-called OXTR genes, which encode receptors for the hormone oxytocin, but Zietsch et al. found no evidence for OXTR linkages.
Consider the following passage, in which Zietsch et al. review other attempts to link human sexual behavior to specific genes:
"Whereas Walum et al. (2008) found association in men (but not women) of a single polymorphism (RS3) with scores on the aforementioned social pair-bonding measure, we find no association of RS3 with extra-pair mating (a related but different measure), and indeed our gene-based association was only significant in women, not in men. Furthermore, we find no evidence of an association of extra-pair mating with OXTR (or the specific SNP rs7632287), which had been previously associated with pair-bonding behaviors in women (Walum et al., 2012). We also did not see any associations between extra-pair mating and the two SNPs rs53576 and rs2254298, which have been suggested to be two promising candidate variants in OXTR. This is in line with a recent meta-analysis reporting no detectable effect of these two OXTR SNPs on human social behaviors (Bakermans-Kranenburg & van IJzendoorn, 2014), but other variants in OXTR have not been as thoroughly examined in past studies and may still warrant further investigation."
That passage—with all its confusion and contradictions--is a microcosm of the history of behavioral genetics. Zietsch et al. note, "Problems with the replicability of candidate-gene associations for behavioral traits are well documented." Indeed. I've been documenting the problems for more than two decades now, and yet the hype persists--even in supposedly responsible outlets like The New York Times. What will it take to stop the gene-whiz hype?