S9SPECIAL REPORT: The Genet ics o f In te l l i gence: E th ics and the Conduct o f Trus tworthy Research

Francis Galton was the first to envision a science that would assess the extent to which a trait like “genius” was due to nature or due to nurture. In

Hereditary Genius, published in 1869, Galton docu-mented several centuries’ worth of British judges, poets, and statesmen and concluded that these eminent men were confined to a relatively small number of families, which he took to point to the “hereditary” origin of such genius.1 From the very beginning, then, studies of na-ture and nurture were focused on understanding human intelligence.

Galton’s interest in investigating the nature and nurture of intelligence was more than mere curiosity about the phenomenon. He wanted to intervene in the world. If human intellect was as hereditary in origin as speed was in dogs, Galton reasoned, then just as the dog breeder could produce a variety of dog with great running ability, “so it would be quite practicable to pro-duce a highly-gifted race of men by judicious marriages during several consecutive generations” (p. 1). In addi-tion to introducing and developing a science of nature versus nurture, Galton envisioned a social program that would draw on the results of that science to shape future generations—what he eventually called “eugenics.”2 For Galton, eugenics was largely a matter of encouraging individuals with desirable traits like high intelligence—“the fit”—to breed more. However, as Galton’s eugenic vision gathered momentum and followers, others fo-cused their efforts on encouraging individuals deemed to have undesirable traits like low intelligence—“the un-

fit”—to breed less. And when encouragement alone was not enough to discourage the unfit from breeding, eu-genicists resorted to more drastic measures, such as ster-ilization.3 From the very beginning, then, studies of the nature and nurture of intelligence were closely associated with an interest in intervening, and those interventions were surrounded by controversy.

The nature of those controversies has not always been the same, however. Geneticists today who study the he-redity of genius are separated by nearly 150 years from Hereditary Genius. In that time, the science and tech-nology have changed dramatically, and so have the in-terventions that have been envisioned in light of those developments. A scientist today can search for particular stretches of DNA and assess whether differences in those stretches are associated with differences in a human trait of interest; a genetic counselor today can genetically test an individual (be it an embryo, fetus, newborn, child, or adult) and provide information about what that genetic result means, allowing for interventions that can range from terminating a pregnancy to prescribing a special diet or chemotherapy. Such a study and such interven-tions would have been unimaginable to Galton, who had no idea about genes, let alone about DNA and ge-netic testing. So when one asks a question like, “Why is studying the genetics of intelligence controversial?,” it is important to realize up front that the answer will be, “It can be controversial for a variety of different reasons, and those reasons have evolved over time.”

The purpose of this essay is to provide a survey of the controversies that surround genetic studies of intel-ligence. With the survey in place, I will then draw out several lessons both for scientists who study the genet-ics of intelligence as well as for science studies scholars (bioethicists, philosophers, historians, sociologists) who

Why Is Studying the Genetics of Intelligence So Controversial?

By james TaBery

James Tabery, “Why Is Studying the Genetics of Intelligence So Controversial?” The Genetics of Intelligence: Ethics and the Conduct of Trustworthy Research, special report, Hastings Center Report 45, no. 5 (2015): S9-S14. DOI: 10.1002/hast.492

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reflect and comment on the controversies surrounding that research.

Race, Equality, and Discrimination: Controversies Arising from the Study of Group Differences

Genetic studies of intelligence today are, for the most part, undertaken by behavioral geneticists. Behavioral

genetics took shape as a discipline in the 1950s and be-came institutionalized in the 1960s with the creation of the Behavior Genetics Association and the publication of textbooks and journals devoted to studying the genetics of complex behaviors. Aaron Panofsky (a contributor to this special report), in his history of the scientific discipline, points out that the first generation of behavioral geneti-cists actively sought to break ties with the earlier eugenic era.4 By the 1950s, the eugenic vision from the previous de-cades had failed, partly due to scientific factors and partly due to social ones. On the scientific side, developments in genetics and the social sciences showed that there was no clear divide between nature and nurture. A trait like in-telligence was the developmental product of interactions among many genes and many environmental exposures. On the social side, it became clear that the entire eugenic vision was based on inherent biases concerning what made one person more valuable than another. The very concep-tions of “fit” and “unfit” were wrapped up in racist and classist ideas about the superiority of middle- and upper-class whites and the traits exhibited by them in comparison to working- and lower-class minority groups and the traits found among them. So the eugenic idea that upper-class whites should breed more because they are the intelligent ones and lower-class minority groups should breed less be-cause they are the less intelligent ones was doubly doomed to fail; intelligence was not solely hereditary in origin, and the presumption that it was fed off the personal biases of the eugenicists promoting the vision.

Behavioral geneticists, Panofsky explains, were intimate-ly aware of this recent history when they sought to create a scientifically and socially respectable discipline that could disassociate itself from the eugenic past. On the scientific side, behavioral geneticists aimed to form a field that was inherently interdisciplinary, one that would bring together both biological and social scientists so that no single em-phasis on nature or nurture could dominate. On the social side, the behavioral geneticists explicitly deemed certain investigations outside the bounds of the discipline; in par-ticular, the study of group differences (that is, differences between races and ethnicities) was too closely aligned with the eugenic shortcomings of the past, and so those studies were omitted from the discipline’s early scientific agenda.

The early behavioral geneticists’ efforts to create a con-troversy-free discipline were interrupted in 1969 when

Arthur Jensen published “How Much Can We Boost IQ and Scholastic Achievement?”5 By the 1960s, it was widely recognized that there existed on average a gap in IQ scores between black and white Americans, and the gap was quite substantial—about fifteen points. The received view at the time was that the gap had an environmental explanation; one of the groups was systematically exposed to things like slavery and poor schooling for several hundred years, while the other was not. To eliminate the gap, then, the thought was that efforts should be targeted at the environmental source of the problem, and so compensatory educational programs like Head Start were created to target and en-rich the early educational environments of disadvantaged children. Jensen, drawing on behavioral genetic research, argued that the IQ gap could not be explained entirely by appeal to environmental differences; rather, much of it was due to genetic differences between blacks and whites. And if this was the case, then efforts aimed at eliminating the gap with environmental interventions were misguided, since black and white Americans were intellectually separated in part by genetic differences. Jensen’s publication kicked off what came to be called the “IQ controversy,” and it was indeed controversial. The data on which he relied were said to have been fabricated; the methodology he used to as-sess the heritability of differences in IQ (that is, the extent to which they were attributable to differences in heredity as opposed to differences in environment) was criticized for being unable to say anything about the actual causes of intelligence; the assumption that there were biologically distinct black and white races was questioned. Still, Jensen had his supporters. A number of prominent scientists de-fended Jensen’s genetic hypothesis, as well as his academic freedom to study such a controversial subject.6

Importantly, these controversial episodes where genetic differences were used to explain race differences were by no means confined to the 1960s and 1970s. In 1994, Richard Herrnstein and Charles Murray’s book The Bell Curve took Jensen’s genetic hypothesis one step further by arguing that the higher intelligent and lower intelligent popula-tions were gradually moving farther and farther apart as individuals within those populations tended to reproduce more often with mates of similar intelligence.7 And then, in 2007, James Watson, who had won the 1962 Nobel Prize for discovering the double-helical structure of DNA, told an interviewer that he was “inherently gloomy about the prospect of Africa” because “all our social policies are based on the fact that their intelligence is the same as ours—whereas all the testing says not really”; while he hoped all people were equal, Watson continued, “[P]eople who have to deal with black employees find this not true.”8 (These comments were widely condemned, and Watson quickly retracted them.9)

S11SPECIAL REPORT: The Genet ics o f In te l l i gence: E th ics and the Conduct o f Trus tworthy Research

One variety of controversy that can attend genetic stud-ies of intelligence, then, follows from studies of group differences generally and race differences specifically. The studies are controversial because they are interpreted to suggest that it is biologically justifiable to treat people from different races differently. They are also controversial be-cause they are interpreted to support a fatalistic acceptance of the IQ gap as an immutable biological reality. So the controversy in this case is about using the genetic studies to justify not intervening—that is, appealing to the genetic difference between blacks and whites to claim that educa-tional efforts designed to eliminate the gap are a waste of money. For some critics of this research, the very fact that the studies support such ideas implies that it is racist sci-ence.10

It is crucial to point out that this research was forcefully attacked from within the behavioral genetics discipline as well as from outside it. In 1972, when some politicians used Jensen’s research to call for pulling governmental support from compensatory educational programs, Irving Gottesman (who has coauthored an essay in this special re-port) was called before the U.S. Senate to explain what be-havioral genetics did and did not support, and Gottesman testified that, while genetic differences contributed some-thing to differences in IQ, that did not mean the IQ gap between blacks and whites was explained by genetics. In fact, he countered, the relatively impoverished educational environment of blacks was the much better explanation.11 And in response to Watson’s comments, Eric Turkheimer (another contributor to this special report) pointed out that the Nobel Prize winner, although an expert on the structure of DNA, was no expert on the genetics of intel-ligence or race differences. “He is, of course, still entitled to his opinion,” Turkheimer granted, “but famous scientists and intellectuals have some responsibility not to use their fame in the service of dangerous ideas that are ultimately outside their real expertise. Watson got in trouble for casu-ally stating poorly informed opinions about a deeply seri-ous subject.”12 For behavioral geneticists like Gottesman and Turkheimer (both past presidents of the Behavioral Genetics Association), the race controversies are costly dis-tractions since they can be used by critics outside behav-

ioral genetics to claim that the discipline is corrupt with racism. The genetic studies of intelligence to which they contribute are aimed at investigating both the genetic and environmental contributions to intelligence, with the goal of using that information to better understand how nature and nurture interplay to contribute to the development of a trait as complex as intelligence—the very research that the first generation of behavioral geneticists envisioned would define the field.13

Genetic Testing, Genetic Essentialism, and Responsibility: Controversies Arising from the Search for Genes

Behavioral genetics underwent a massive shift in the 1990s. Traditionally, its methods had included a variety

of family, adoption, and twin studies, where the goal was to assess how much of the total variation in a trait of interest was attributable to the various genetic and environmen-tal causes of variation. The heritability score was one such product of these methods. And while a heritability score could say something about how much of the variation in IQ in some population was due to the genetic differences in that population, it could not say which genes were im-plicated in those differences or what biological mechanisms linked up the genetic differences to the variation in IQ. In the 1990s, behavioral geneticists co-opted developments in molecular genetics, such as linkage and association stud-ies, as well as developments in the public funding of sci-ence, such as the Human Genome Project, to transition to searching for specific genes.

The behavioral geneticist who most embodies this evo-lution in the field is Robert Plomin. Plomin has been inves-tigating the genetics of intelligence for four decades now, and over that time, he has undertaken a variety of studies of twins and adoptees to assess the extent to which genetic differences are associated with differences in intelligence.14 Those studies have shown, for example, that the heritabil-ity of intelligence increases with age (that is, that genetic differences account for more and more of the variation in intelligence as people get older) and that subcomponents of intelligence (such as verbal ability, spatial ability, and mem-

Certain genetic studies of intelligence have been used to claim that educational efforts designed to eliminate the IQ gap between

blacks and whites are a waste of money. This research has been forcefully attacked from within the behavioral genetics discipline

as well as from outside it.

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ory) have their own unique heritability scores.15 Starting in the 1990s, Plomin supplemented those twin and adoption studies with molecular studies aimed at discovering the genes responsible for differences in intelligence.16

Despite early optimism, however, even advocates for this research like Plomin have come to admit that the process has gone slower than expected.17 There are apparently no genes that have a large effect on variation in intelligence in the normal range, and so studies that include even several thousand participants with a broad range of intelligence levels have failed to identify promising genetic candi-dates.18 One approach to this problem has been to under-take studies with much larger sample sizes. A study with over 100,000 participants, for example, allowed researchers to identify three promising genetic variants.19 Nonetheless, those three variants accounted for only a small fraction of the variation in intelligence; an individual who received both copies of all three variants would on average score less than two IQ points higher than someone who inherited none of them.20 Another approach to the problem has been to focus more attention on the very high end of the intel-ligence spectrum. In 2007, Plomin oversaw the creation of the Consortium on the Genetics of High Cognitive Abilities,21 which in 2012 teamed up with the Cognitive Genomics division of BGI, a Chinese genome-sequencing institute, to examine whether the genetic architecture of the very high end of the intelligence spectrum could shed light on the general phenomenon and also help elucidate the genetic origins of intellectual disability.22

A new set of controversies arose from these molecu-lar searches for genes. Whereas the earlier controversies stemmed from group membership and differences between groups, the hunt for specific genes raises concerns that per-tain more to individuals with their individual genomes. When news broke of BGI’s interest in the genetics of high intelligence, one story, headlined “China Is Engineering Genius Babies,” suggested that the research was part of a larger plan for global domination.23 With even the most promising genetic candidates accounting for a very small fraction of variation in intelligence, Galton’s early eugen-ic vision of creating a “highly-gifted race of men” is far-fetched to say the least. Still, there is a genuine concern that when it comes to a technology like preimplantation genetic diagnosis, where one or more embryos are selected for implantation rather than other embryos based on the genetic profiles of the embryos, something like a new eu-genics might emerge.24 It is ludicrous to label an individual with an IQ of 101 “fit” and an individual with an IQ of 99 “unfit,” but if parents are deciding which of two embryos to implant and the genetic counselor explains that one em-bryo has the genetic variants associated with the ever-so-slightly increased IQ found in the 2014 study to which Plomin contributed, would they take that into consider-

ation when deciding which embryo to implant? If they did, it is hard not to interpret it as a judgment about what makes one potential life more valuable than another—even if the difference between the two is practically negligible. That act of ranking the value of others’ lives harkens back to the eugenic ideology of the past, and so genetic testing technologies of the present bring with them that contro-versy.

Molecular technologies also raise concerns about genetic reductionism and genetic essentialism, as well as about the impact on issues ranging from moral responsibility to per-sonal identity.25 It is one thing to say “genes are somehow involved” in the existence of differences in intelligence—and that’s all the early twin and adoption studies could say. The molecular search for individual genes, in contrast, at-tempts to implicate specific genes—specific causal agents, with specific names (like “KNCMA1”) and specific func-tions (like producing proteins involved in neurotransmis-sion). This explanatory act of genetic reductionism often brings with it an associated aura of genetic essentialism, wherein the genetic aspect to the explanation swamps other causally relevant factors, resulting in the conceptualization of the trait of interest as a genetic trait.26 Genetic essen-tialism, in turn, brings with it a range of cognitive biases concerning, for example, the immutability of the genetic trait.27 If genes associated with intelligence are found, the concern goes, then no matter how small the genetic effect, people will think of intelligence as a genetic trait, will pay less attention to environmental influences on intelligence (with even greater effect sizes), and will shift responsibility for cognitive achievement from individuals to individuals’ genes.

Lessons from the Controversies

There are lessons to be drawn from this brief survey of the controversies surrounding genetic studies of in-

telligence—lessons for both the scientists who do that re-search and the outsiders (such as bioethicists, philosophers, and historians) who reflect and comment on those contro-versies. Let me start with the latter. Controversial science is intriguing and garners attention, so it is not surprising that commentators from a variety of disciplines are drawn to the topic. Historians uncover the origins of controver-sy; philosophers assess the epistemological stakes of con-troversy; sociologists investigate the social structures that facilitate and perpetuate controversy; bioethicists consider the ethical, legal, and social implications of controversy; science journalists explain controversy for the public.

For commentators on genetic studies of intelligence, the first lesson to bear in mind is that the research can be controversial for a variety of reasons, and it is important to bear those differences in mind when assessing the science.

S13SPECIAL REPORT: The Genet ics o f In te l l i gence: E th ics and the Conduct o f Trus tworthy Research

Now, occasionally a scientist will undertake and publish research that spans both the gene-hunting and group-differences controversies; Bruce Lahn, for instance, made headlines in 2005 when he reported identifying two genes associated with brain development that were common in Eurasian populations and rare in sub-Saharan African populations, a difference that purportedly accounted for what were deemed to be the historically more significant cultural achievements of the former in comparison to the latter.28 But this overlap need not exist. For example, a molecular geneticist searching for genes associated with intelligence may have no interest at all in finding different frequencies of those genes in different racial groups (and no expectation of finding them). That researcher would face all the controversy associated with attempting to link up individual differences in intelligence to differences in in-dividuals’ genomes, but it would be unfair to associate her research with the controversy surrounding something like racial discrimination, since no race differences were sought or expected.

The second lesson is that a scientist can be interested in studying the genetics of intelligence with no interest in and no expectation of finding either genetically influenced race differences or specific genes that account for individual dif-ferences in intelligence. Turkheimer occupies this space. He has spent decades drawing on the tools of behavioral genetics to understand the nature and nurture of intelli-gence, but throughout that period he has also been highly critical of both efforts to explain the IQ gap between blacks and whites by appeal to genetic differences as well as efforts to identify specific genes that will account for any signifi-cant portion of the individual differences in intelligence. Turkheimer has instead studied and emphasized environ-mental differences between blacks and whites and drawn attention to the effects of random life experiences on in-dividual differences.29 This research receives less scrutiny from outsiders precisely because it does not lend itself to charges of discrimination or of fostering a new eugenics. But for any commentator interested in assessing genetic studies of intelligence, an analysis that focuses only on the controversial science does a disservice to the range of ways that that research can be undertaken, not all of which nec-essarily contribute to controversy.

There are also two lessons for the scientists who under-take research on genetic contributions to intelligence, both having to do with keeping a distance from race-differences research in the field. As mentioned above, practicing behav-ioral geneticists often bemoan episodes like the IQ contro-versy, the Bell Curve debate, and Watson’s comments; the study of the genetic contributions to race differences is seen as fringe research that too often distracts attention from other research in the field. But the scientist aiming to keep race research at arm’s length must remember that genetics is the study of differences, and race differences are just one of many differences that can be examined when genetic stud-ies are undertaken. An individual scientist might say that he is not personally interested in studying race differences, and an entire discipline such as the first generation of be-havioral geneticists could deem race-differences research outside the bounds of mainstream work. But the prospect of work on race differences will always lurk at the edges be-cause it will always be possible to ask, for any given genetic difference, whether that genetic difference influences a race difference. That is precisely what Jensen did in 1969. He simply took a wide body of behavioral genetics research (having nothing to do with race) concerning the contribu-tion of genetic differences to individual differences in IQ and extended it to try to explain a group difference. The same goes for contemporary molecular genetic research searching for specific genes associated with differences in intelligence. The scientists doing that research may say they have no interest in investigating race differences in the genes they seek. But that does not prevent another scientist from investigating whether the genes identified are distrib-uted with different frequencies in different racial groups.

Moreover, and this is the second lesson for the scientists, it is important to remember that even if the community could keep race research at bay and out of the newspaper headlines, research on the genetics of intelligence would still not be expunged of all controversy. For, as the survey of gene-hunting studies above conveys, there are a whole set of unique controversies that surround that side of the research. Concerns about genetic testing facilitating a new eugenics, concerns about genetic explanations contributing to misleading ideas about genetic essentialism, and con-cerns about responsibility and blame eroding in the face of

There is a genuine concern that when it comes to preimplantation genetic diagnosis, where one or more embryos are selected rather than

others based on their genetic profiles, something like a new eugenics might emerge.

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that genetic essentialism all arise from molecular genetic re-search even if no race differences are ever sought or found.

1. F. Galton, Hereditary Genius, an Inquiry into Its Laws and Consequences (London: Macmillan and Co., 1869).

2. F. Galton, Inquiries into Human Faculty and Development (London: Macmillan and Co., 1883).

3. D. J. Kevles, In the Name of Eugenics: Genetics and the Uses of Human Heredity (Cambridge, MA: Harvard University Press, 1995).

4. A. Panofsky, Misbehaving Science: Controversy and the Development of Behavior Genetics (Chicago: The University of Chicago Press, 2014); see also A. Panofsky, “What Does Behavioral Genetics Offer for Improving Education?,” The Genetics of Intelligence: Ethics and the Conduct of Trustworthy Research, special report, Hastings Center Report 45, no. 5 (2015): S43-S49.

5. A. R. Jensen, “How Much Can We Boost IQ and Scholastic Achievement?,” Harvard Educational Review 39 (1969): 1-123.

6. For an overview of the many sides to the controversy, see S. H. Aby and M. J. McNamara, eds., The IQ Debate: A Selective Guide to the Literature (New York: Greenwood Press, 1990).

7. R. J. Herrnstein and C. Murray, The Bell Curve: Intelligence and Class Structure in American Life (New York: The Free Press, 1994).

8. C. Hunt-Grubbe, “The Elementary DNA of Dr. Watson,” The Sunday Times, October 14, 2007.

9. C. Dean, “Nobel Winner Issues Apology for Comments about Blacks,” New York Times, October 19, 2007.

10. A. Chase, The Legacy of Malthus: The Social Costs of the New Scientific Racism (Urbana: University of Illinois Press, 1980).

11. I. Gottesman, “Testimony Submitted to United States Senate Select Committee on Equal Educational Opportunity, February 24, 1972” (U.S. Senate Select Committee on Equal Educational Opportunity, 1972).

12. E. Turkheimer, “Race and IQ,” Cato Unbound, November 21, 2007, accessed July 28, 2015, at http://www.cato-unbound.org.

13. E. Turkheimer et al., “Socioeconomic Status Modifies Heritability of IQ in Young Children,” Psychological Science 14 (2003): 623-28; R. E. Nisbett et al., “Intelligence: New Findings and Theoretical Developments,” American Psychologist 67 (2012): 130-59; see also E. Turkheimer, “Genetic Prediction,” The Genetics of Intelligence: Ethics and the Conduct of Trustworthy Research, special report, Hastings Center Report 45, no. 5 (2015): S32-S38.

14. R. Plomin and J. C. DeFries, “Genetics and Intelligence: Recent Data,” Intelligence 4 (1980): 15-24.

15. G. McClearn et al., “Substantial Genetic Influence on Cognitive Abilities in Twins 80 or More Years Old,” Science 276 (1997): 1560-63; C. M. A. Haworth et al., “The Heritability of

General Cognitive Ability Increases Linearly from Childhood to Young Adulthood,” Molecular Psychiatry 15 (2010): 1112-20.

16. R. Plomin and S. A. Petrill, “Genetics and Intelligence: What’s New?,” Intelligence 24 (1997): 53-77; R. Plomin, “Genetics and General Cognitive Ability,” Nature 402 (1999): C25-C29.

17. R. Plomin, J. K. J. Kennedy, and I. W. Craig, “The Quest for Quantitative Trait Loci Associated with Intelligence,” Intelligence 34 (2006): 513-26.

18. O. S. Davis et al., “A Three-Stage Genome-Wide Association Study of General Cognitive Ability: Hunting the Small Effects,” Behavior Genetics 40 (2010): 759-67.

19. C. A. Rietveld et al., “Common Genetic Variants Associated with Cognitive Performance Identified Using the Proxy-Phenotype Method,” Proceedings of the National Academy of Sciences 111 (2014): 13790-94.

20. B. Benyamin and P. Visscher, “Intelligence Inheritance—Three Genes that Add to Your IQ Score,” The Conversation, September 8, 2014.

21. C. M. A. Haworth et al., “A Twin Study of the Genetics of High Cognitive Ability Selected from 11,000 Twin Pairs in Six Studies from Four Countries,” Behavior Genetics 39 (2009): 359-70.

22. E. Yong, “Chinese Project Probes the Genetics of Genius,” Nature 497 (2013): 297-99.

23. A. Eror, “China Is Engineering Genius Babies,” VICE, March 15, 2013, accessed July 28, 2015, at http://www.vice.com/en_us.

24. G. Allen, “Is a New Eugenics Afoot?,” Science 294 (2001): 59-61.

25. E. Parens, “Genetic Differences and Human Identities: On Why Talking about Behavioral Genetics Is Important and Difficult,” supplement, Hastings Center Report 34, no. 1 (2004): S1-S36.

26. D. Nelkin and M. Lindee, The DNA Mystique: The Gene as a Cultural Icon (Ann Arbor: University of Michigan Press, 2004).

27. I. Dar-Nimrod and S. J. Heine, “Genetic Essentialism: On the Deceptive Determinism of DNA,” Psychological Bulletin 137 (2011): 800-18.

28. On this controversy, see S. S. Richardson, “Race and IQ in the Postgenomic Age: The Microcephaly Case,” BioSocieties 6 (2011): 420-46, as well as Richardson’s contribution to this special report: “The Trustworthiness Deficit in Postgenomic Research on Human Intelligence,” The Genetics of Intelligence: Ethics and the Conduct of Trustworthy Research, special report, Hastings Center Report 45, no. 5 (2015): S15-S20.

29. E. Turkheimer, “Three Laws of Behavior Genetics and What They Mean,” Current Directions in Psychological Science 9 (2000): 160-64; Nisbett et al., “Intelligence: New Findings and Theoretical Developments,” 130-59.