In 1990 The New York Times published a front-page article by Lawrence Altman, a reporter with a medical degree, announcing that scientists had discovered "a link between alcoholism and a specific gene." That was merely one in a string of reports in which the Times and other major media hyped what turned out to be erroneous claims linking complex traits and disorders—from homosexuality and high intelligence to schizophrenia and bipolar disorder—to specific genes. ADVERTISEMENT I thought those days were over, and that scientists and the media have learned to doubt extremely reductionist genetic accounts of complex traits and behaviors. I was wrong. Last Sunday, the "Opinion" section of the Times published an essay, "The Feel-Good Gene," which states: "For the first time, scientists have demonstrated that a genetic variation in the brain makes some people inherently less anxious, and more able to forget fearful and unpleasant experiences. This lucky genetic mutation produces higher levels of anandamide--the so-called bliss molecule and our natural marijuana--in our brains. In short, some people are prone to be less anxious simply because they won the genetic sweepstakes and randomly got a genetic mutation that has nothing at all to do with strength of character." This article, like the one touting the alcoholism gene 25 years ago, was written by a physician, Richard Friedman, professor of psychiatry at Weill Cornell Medical College. I emphasize this fact because scientific hype is often blamed on supposedly ignorant journalists like me rather than on physicians and other so-called experts. Here is the scientific backstory. The "feel-good gene" is a variant, or allele, of a gene that produces an enzyme called fatty acid amide hydrolase, FAAH. FAAH is thought to regulate levels of the neurotransmitter anandamide, an endogenous cannabinoid structurally similar to tetrahydrocannabinol, THC, the primary psychoactive ingredient of marijuana. An allele of the FAAH gene, sometimes called 385A, has been associated with lower levels of FAAH, which result in higher levels of anandamide. An estimated 20 percent of Americans carry the 385A gene. Friedman's article is, in effect, an extremely dumbed down, sensationalized press release for a highly technical article in Nature Communications by 16 researchers, including two of Friedman's colleagues at Weill Cornell Medical College, Iva Dincheva and Francis Lee. ADVERTISEMENT The bulk of the article, "FAAH genetic variation enhances frontal amygdala function in mouse and human," describes elaborate experiments on mice into which the 385A allele has been inserted. The article also describes experiments on humans. I'm focusing on this human research, which is also the primary focus of Friedman's Times article. Dincheva and Lee's group carried out a two-part experiment on 40 humans, including 18 carriers of the 385A allele. In the first stage of the experiment, called "fear acquisition," subjects were shown various neutral images, such as colored squares. Particular colors, such as yellow, were repeatedly followed by an "aversive" stimulus--such as a loud noise or scary image, like a snarling dog--so that subjects became conditioned to associate the first stimulus with the second. In the second part of the experiment, called "fear extinction," subjects were shown the colored squares without subsequently being exposed to the "aversive" stimulus. During the experiments, researchers measured subjects' skin conductance by means of electrodes attached to their fingers. High skin conductance indicates more sweating which supposedly indicates more "fear" in response to the aversive stimulus. newsletter promo Sign up for Scientific American’s free newsletters. Sign Up So what were the results of Dincheva and Lee et al.? During the "fear extinction" trials, the 385A subjects had a more persistent skin-conductance response to colors that had previously been associated with a noise. The researchers also reported that 385A carriers scored higher on questionnaires that probed their levels of anxiety. These latter findings are the basis for Friedman's claim that the researchers "demonstrated"—note the absence of qualification in that word—that 385A carriers are "inherently less anxious, and more able to forget fearful and unpleasant experiences." ADVERTISEMENT Friedman does not question the assumptions of the fear acquisition and extinction experiments: first, that someone's response to a noise or image of a dog in a laboratory setting can serve as a proxy for "anxiety" in all its myriad manifestations; second, that skin conductance measures anxiety. (Fun facts: commercial lie detectors, which are notoriously unreliable, measure skin conductance, and so do the "E-meters" with which Church of Scientology "audits" people.) Friedman only briefly mentions that the researchers found no significant difference between the 385A subjects and other subjects in their initial response to