Prefatory Note to The Twin Research Debate

Small assumptions can make colossal differences. Tobacco is safe. What’s good for Wall Street is good for Main Street. Genes influence everything we do – and twin studies allegedly prove it. Even when a myriad of environmental and social factors actually are acknowledged, genes nevertheless are said to affect everything that matters about human behavior, at least “in part” (whatever that may mean), and that this crucial role is supposed to deserve unquestioned assent and to command a substantial amount of collective resources. Gene research, after all, is pricey. Given the questionable foundations of the science, and what’s at stake, we should not allow ourselves to be seduced by the statistical pyrotechnics of the proponents.

According to this modern scientistic gospel, there is a gene, or an interacting group of genes, behind every mental disorder, act of criminality, and political inclination.[1] Note the obligatorily rhetorical piece “Do Genes Determine How you Vote?” – with implied affirmative answer – in the highly reputable British newspaper The Independent during the 2015 election.[2] Stenographic science reporters routinely relay claims that a gene for this or that condition has been nabbed, and reckon that the cure, in the form of a profitable pill or physical intervention, cannot be far behind. As glum critics long have observed, these assertions always are blazed in headlines, and always soon are retracted, or hedged into oblivion, in small print.[3] Nothing has changed. On the day this piece goes off to layout a gaggle of scientists announced they have found a gene ‘associated with thinking skills,’ results which they caution ‘remain to be replicated.’[4]

Most genetic researchers nowadays recognize that environmental factors play some sort of role, yet, based on their genetocentric interpretations of twin studies, clearly subscribe even more so to the existence of congeries of many genes of varying effect size that play an important part in causing behavioral characteristics and disorders. These researchers usually stipulate that preliminary gene association results need to be replicated. At the same time, journalists in major media outlets frequently sensationalize their work and lead the public to believe that the ‘smoking gene,’ as it were, for any given behavior has been nabbed. Even after replication attempts fail, these accounts leave the false impression among the general public that genes causing strong behavior differences have been located, if not caged.

Any infinitesimal statistical correlation typically is hailed as a harbinger of a clinching proof. Genes are deterministic in the sense that whatever behavior you care about, the person who exhibited it undeniably possessed genes, period. While the history of science shows that enthusiasm for a hypothesis can indeed be an asset, the accompanying urge to overlook contradicting factors is a common and dangerous one.[5] Researchers rarely see what they are not looking for, especially if their paychecks, as that noted investigator of the human condition Mark Twain remarked, depend on not seeing it.[6] The current cultural climate renders citizens easy prey to overhyped non-discoveries. Keep in mind that everyone engaged in gene research, even the most talented and skeptical practitioners, benefits materially from these misapprehensions.

Even when making allowances for environmental influences, researchers typically shortchange this factor so as to maintain perhaps the most expensive snipe hunt in history. Human experience is not supposed to matter very much or, in some formulations, at all. If it did, we might behold an overdue spate of widely publicized genuine critical reflections about all the blanks these researchers are drawing. Scientists, being human, often resort to ad hoc statements and other extenuating justifications to pursue research aligning with expectations of what they will find. This phenomenon is particularly egregious in the avid hunt for genetic causes of criminality and psychoses. In a 2009 Nature article “Finding the Missing Heritability,’ several prominent researchers, poring over a dismal record of non-findings for genetic causation, wind up advocating more of the same because they are so certain the genes are ‘out there.”[7] For them heritability is at the core. Heritability, however, is a woefully and easily misunderstood concept but it is misunderstood to the advantage of those who believe we inherit our behavioral (hot temper) as well as physical traits (red hair).[8]

Much of the misplaced confidence in genetic explanations stems from studies of fraternal and identical twins. The general public has no idea how dubious these studies actually are, reanimated lately by what is termed a trait-relevant Equal Environment Assumption; hence, the debunking intervention below. The artful ad hoc-ery of this explanatory strain goes so far as claiming that identical twins ‘create their own environment,’ rather than the environment – say, parents with four figure incomes versus parents with six or seven figure incomes – influencing them. More on this in the main article below. The formidable co-authors argue on ample evidence that the classical twin design has outlived its natural scientific life because it is perpetuated by a set of assumptions or defenses that are starkly circular. Assumptions fuel conclusions (only genes matter) at the same time that those conclusions are used as a rationale for the assumptions. If there is no ‘smoking gene’ then the public is entitled to ask what exactly the money is being doled out to do?

Outside the alluring artificial framework of twin research design, it is extremely apparent that a lousy and deprived upbringing, no matter what your gene make-up, can make you miserable and vulnerable.[9] Human adaptation is dominated by environmental sensitivity that is only weakly influenced by genetic variation, and is powerfully influenced by the contingencies of our specific socioecological niches. It is clear and well established that the environment seriously affects the development of any child. So the co-authors consider it highly relevant to analyze whether identical twins are more similar on this account than fraternal twins. Because beliefs influence public policy, the stakes are huge.



[1] Merriam’s Dictionary online entry for ‘scientism’ is perhaps too apt. The second (2) definition, as intended here, is “an exaggerated trust in the efficacy of the methods of the natural sciences to all areas of investigation (as in philosophy, the social sciences, and the humanities).” The first (1) definition, though, is “methods and attitudes typical of or attributed to the natural scientist (!)'[exclamation point mine]. www.merriam See the 2013 exchange about the concept between Stephen Pinker and Leon Wieseltier at

[2] Noting that causation instead runs both ways between genome and environment, see Evan Charney and William English, ‘Candidate genes and Political Behavior,’ American Political Science Review February 2012, p. 30.

[3] For background see Kurt Jacobsen, ‘The Mystique of Genetic Correctness’ Logos, 6, 1 (Winter-Spring 2007).

[4] One sincerely hopes they confirm it this time and manage to put it to some use themselves. ‘Researchers find Gene associated with Thinking Skills,” Medical Press 15 July 2015.

[5] On the difference between ‘logic of discovery’ (where hunches and hopes abound) and ‘logic of justification’ see Karl Popper, The Logic of Scientific Discovery (New York: HarperCollins, 1974, rev.).

[6] Upton Sinclair can be credited with a less folksy formulation, which I have tapped, of Twain’s observation that “You tell me whar a man gits his corn pone an’ I’ll tell you what his ‘pinions is.” The posthumously published essay ‘Corn Pone Opinions’ can be found in Mark Twain, What is Man? And Other Philosophical Writings (Berkeley: University of California, 1973). Ed. Paul Baender.

[7] Teri A. Manolio et. al. ‘Finding the Missing Heritability of Complex Diseases’ Nature: International Weekly Journal of Science 461, 8 October 2009.

[8] Heritability is a population statistic with scarcely any predictive power regarding, or applicability to, individuals. For a concise critique see Jay Joseph, “Are DSM Psychiatric Disorders ‘Heritable?’ Madness in America Blog 24 June 2015

[9] See, for example, Kate Pickett and Richard G Wilkinson, The Spirit Level: Why More Equal Societies Almost Always Do Better (London: Penguin, 2010) and Anthony Atkinson, Inequality – What Can be Done? (Cambridge: Harvard University Press, 2015).


Kurt Jacobsen is a Logos editor, a research associate at the University of Chicago, and the author of Technical Fouls: Democratic Dilemmas and Technological Change and of Freud’s Foes: Psychoanalysis, Science and Resistance.


Latest Issue

2024: Vol. 23, No. 1

Latest Issue

2024: Vol. 23, No. 1

By Michel Kail , Richard Sobel: Economic Crisis and the Crisis in Economic Thought A Progressive-Iconoclastic Perspective Inspired by Sartre

By Frank Kirkland: The Questionable Legacy of Brown v. Board of Education: Du Bois’ Iconoclastic Critique

By Lori Watson: What Is a “Woman” Anyway?

By Kevin Anderson: Four Years After the Arab Revolutions: Fighting on Amid Reactionary Retrenchment

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By Brian Caterino: The Practical Import of Political Inquiry: Perestroika’s Last Stand

By Mark Worrell: Moral Currents in Durkheim and Huysmans

By Chris Byron: A Critique of Axel Honneth’s Theory of Reification

By Kurt Jacobsen: Prefatory Note to The Twin Research Debate

By Jay Joseph , Claudia Chaufan , Ken Richardson , Doron Shultziner , Roar Fosse , Oliver James , Jonathan Latham: The Twin Research Debate in American Criminology

By Leonard Quart , Al Auster: Hollywood Follows the Money: Films of the ‘Great Recession’

By Tony Lack: Slavoj Žižek: Absolute Trouble or Recoil in Paradise?

By Brian Trench: Gabriella Coleman, Hacker, Hoaxer, Whistleblower, Spy – the many faces of Anonymous

By Kurt Jacobsen: Daniel P. Bolger, Why We Lost: A General’s Inside Account of the Iraq and Afghanistan Wars

By Riad Azar: Michael Gould-Wartofsky, The Occupiers

By Linda Etchart: Eduardo Galeano, Children of the Days: A Calendar of Human History

By Benjamin J. Pauli: Murray Bookchin, The Next Revolution: Popular Assemblies and the Promise of Direct Democracy