The Heritability of Human Behavior: Results of Aggregating Meta-Analyses

The heritability of human behavior can be estimated through studies comparing MZ and DZ twins and through adoption studies. Meta-analyses have estimated the heritability of intelligence, mental chronometric performance, language ability, anxiety disorders, major depression, antisocial behavior, problem drinking, and smoking. This article presents the aggregation and analysis of these meta-analyses, which included a total of over four hundred samples. The results of the aggregation suggest that about 41% of human behavior is genetically influenced, a percentage that may have evolutionary value. Some significant moderators were found in more than one meta-analysis, including greater heritability (a) in more disordered levels of a behavior for performance on a language-ability test, antisocial behavior, and smoking and (b) in females for antisocial behavior and smoking initiation. The moderator findings raise questions about what might explain the identified differences in level of heritability.     

Don't throw the bathwater in with the baby

The Presidential Address of the European Association of Developmental Psychology, Goossens (2012, this issue), this year concerned how genes and environments interplay to shape loneliness and other developmental psychological relevant outcomes. This is a very welcome. However, when developmental psychology is now ready to integrate recent genetic and neuroscience knowledge and methods, I think it would be very wise not to go uncritically through the mistakes that have been made in other disciplines and instead to learn from their hard lessons. I discuss some problems (genes vs. environments, identifying genes for a phenotype, environmental causes of developmental outcomes, and gene×environment interaction and epigenetics) and some suggestions for solutions that can be used to avoid throwing the bathwater in with the baby.     

Casual Cynics or Disillusioned Democrats? Political Alienation in Japan

This paper examines the structure of political alienation among Japanese eligible voters, using data from the first, second, fifth, and sixth waves of the seven-wave Japanese Electoral Survey II (JES II). Political alienation can be expressed as comprising two dimensions, political trust and civic-mindedness. Males and people with more years of schooling are more allegiant in general; that is, they are both more trusting and more civic-minded. Evaluations of cabinet performance and support for democratic mechanisms are strongly related to political trust and civic-mindedness. Supporters of the Liberal Democratic Party (LDP) are no more civic-minded than average but are more trusting politically, whereas Japan Communist Party supporters are more civic-minded but a good deal less politically trusting than average. Independents are below the overall average on both the political trust and civic-mindedness dimensions. Even though party support is unstable, Japan's political system will not lose its stability as long as LDP supporters and independents constitute the majority of Japan's electorate. The advent of a new party capable of providing an alternative to the LDP is important to the future of Japanese democracy.     

Understanding the relation between explicitly and implicitly measured political orientation: The moderating role of political sophistication

Researchers have argued that to understand more fully political orientation, non-reactive measures similar to those used in the broader implicit attitudes literature should be explored. Recently, the nature of the relation between explicitly and implicitly measured attitudes has been a topic of considerable discussion, with researchers stressing the importance of when explicit and implicit measures are related and when they are not. In the present research, the relation between explicit and implicit political orientation, and the potential moderating role of political sophistication was investigated. Participants (N = 116) completed an explicit measure of political orientation, a liberal–conservative Implicit Association Test (IAT), and a test of political knowledge. Results showed that explicit and implicit political orientation scores were moderately correlated (r = .48) with each other. Moreover, results from regression analyses showed that the association between explicit and implicit political orientation was moderated by political knowledge scores, such that the positive association was stronger among participants with a greater knowledge of politics.     

Hungry for love: the influence of self-regulation on infidelity

The current research examines the effect of self-regulation on the likelihood of committing infidelity. Thirty-two college students in exclusive romantic relationships interacted through a private chat room with an opposite-sex confederate. Prior to this interaction, a food-restriction task depleted half the participants of self-control. As predicted, depleted levels of self-regulation increased the likelihood of infidelity. Specifically, depleted participants were more likely to both accept a coffee date from and supply a personal telephone number to the confederate than non-depleted participants. Weakened self-control may be one potential cause for the levels of infidelity occurring in romantic partnerships today.     

Perceptions of Anti-Semitism among American Jews, 2000–05, A Survey Analysis

Despite their high degree of economic, educational, social, and political success, most American Jews in the early 2000s see anti‐Semitism as a problem, and significant percentages see anti‐Semitism as a very serious problem. How do we explain these perceptions of anti‐Semitic threat given the comparative success of Jews in so many aspects of American life? This paper uses annual surveys from the National Survey of American Jews from 2000 through 2005 to address this question. Results indicate a multiplicity of factors affect perceptions of the seriousness of anti‐Semitism. Those with a stronger sense of Jewish identity, lower income, and older people are more likely to see anti‐Semitism as a very serious problem. Respondents also tend to see anti‐Semitism as a more serious threat if they live in states with higher anti‐Semitic incidents rates and when use of anti‐Semitic terms in the news media increases. The conclusion puts the findings into perspective and suggests what we can learn by studying successful minority groups.     

The genetic basis of entrepreneurship: Effects of gender and personality

Extending previous research on the genetic underpinnings of entrepreneurship, we investigate gender differences in the genetic influences on the tendency of people to become entrepreneurs. We also examined two mediating variables through which genetic factors may impact this tendency: extraversion and neuroticism. Based on 1285 pairs of identical twins (449 male and 836 female pairs) and 849 pairs of same-sex fraternal twins (283 male and 566 female pairs), we found that females have a strong genetic influence and zero shared-environmental influences on their tendency to become entrepreneurs. In contrast, males show zero genetic influence, but a large shared-environmental influence. Extraversion and neuroticism mediate the genetic influences on women’s tendency to become entrepreneurs, whereas extraversion mediates shared-environmental influences on men’s tendency to become entrepreneurs. We discuss this sharp difference in genetic influences on entrepreneurship across gender groups and highlight the different challenges that men and women face in their entrepreneurial endeavors.     

On the heritability of inspection time and its covariance with IQ: a twin study

Using the classical twin design, this study investigates the influence of genetic factors on the large phenotypic variance in inspection time (IT), and whether the well established IT–IQ association can be explained by a common genetic factor. Three hundred ninety pairs of twins (184 monozygotic, MZ; 206 dizygotic, DZ) with a mean age of 16 years participated, and 49 pairs returned approximately 3 months later for retesting. As in many IT studies, the pi figure stimulus was used and IT was estimated from the cumulative normal ogive. IT ranged from 39.4 to 774.1 ms (159±110.1 ms) with faster ITs (by an average of 26.9 ms) found in the retest session from which a reliability of .69 was estimated. Full-scale IQ (FIQ) was assessed by the Multidimensional Aptitude Battery (MAB) and ranged from 79 to 145 (111±13). The phenotypic association between IT and FIQ was confirmed (−.35) and bivariate results showed that a common genetic factor accounted for 36% of the variance in IT and 32% of the variance in FIQ. The maximum likelihood estimate of the genetic correlation was −.63. When performance and verbal IQ (PIQ & VIQ) were analysed with IT, a stronger phenotypic and genetic relationship was found between PIQ and IT than with VIQ. A large part of the IT variance (64%) was accounted for by a unique environmental factor. Further genetic factors were needed to explain the remaining variance in IQ with a small component of unique environmental variance present. The separability of a shared genetic factor influencing IT and IQ from the total genetic variance in IQ suggests that IT affects a specific subcomponent of intelligence rather than a generalised efficiency.     

Socialization and development of the work ethic among adolescents and young adults

Work ethic is part of a broader field of attitudes, identified as cultural conservatism. The results of this longitudinal study—three repeated measurements with 620 adolescents and one of their parents as participants—show that parents' social economic status and educational level are associated with their cultural conservatism, and with the educational level and cultural conservatism of their children. During adolescence, parents effectively transfer their own cultural (non-)conservatism to their children. These socialization factors of adolescent cultural conservatism and adolescent educational level are important determinants of their work ethic. Lower educational level and higher cultural conservatisms of adolescents predict a stronger work ethic. Work ethic is a stable type of attitude, with work ethic at a younger age strongly predicting work ethic at a later age.     

What if there were no God? Politically conservative and liberal Christians imagine their lives without faith

A sample of devout Christian adults, ranging widely in political orientation, described what their lives (and the world) might be like had they never embraced faith. Politically conservative Christians (also scoring high on right-wing authoritarianism) tended to imagine a life deficient in impulse control, wherein unrestrained sexual and aggressive urges, addictive behaviors, and human selfishness undermined the social good. By contrast, politically liberal Christians (also scoring low on right-wing authoritarianism) imagined an empty and barren world, devoid of the emotional intensity that makes life worth living. Gender differences were also observed, but they did not interfere with the relation between political orientation and the narrative themes. In accord with theoretical writings regarding normative and humanistic ideologies, the findings suggest that, at least among American Christians, political conservatism may entail a fear of, or strong sensitivity to, the prospects of conflict and chaos, whereas political liberalism may entail an equally strong fear of, or sensitivity to, emptiness.     

Basic value orientations and moral foundations: Convergent or discriminant constructs?

This study examined the structural and genetic links between value orientations, based on the theory of basic values, and moral concerns, based on moral foundations theory. We hypothesized both structural and genetic convergence of Conservation (versus openness to change) with Binding foundations and of Self-transcendence (versus self-enhancement) with Individualizing foundations. We analyzed self- and informant ratings from 924 participants with extended multitrait-multirater modeling and ran twin model analyses on self-ratings from 555 twin pairs. For Conservation and Binding foundations, we found partial convergence across different rater perspectives and a substantial genetic overlap, but also distinct genetic factors. Self-transcendence and Individualizing foundations were found to be structurally divergent, but genetically linked. We discuss the conceptual and measurement-related implications of the findings.     

More Royalist Than the King? Immigration Policy Attitudes Among Naturalized Citizens

Social psychological research has analyzed immigration attitudes mostly from the perspective of natives without an immigrant background. Nevertheless, an increasing number of migrants obtain national citizenship and take a stance towards immigration policies. By studying immigration policy attitudes reported by naturalized citizens, this article develops a dual-pathway model of immigrant political incorporation featuring pathways of either absorption or transformation. Based on a unique sample of immigrants who just accomplished the naturalization procedure (N = 566), we investigate participants' preferences for permissive or restrictive immigration policies as a function of their naturalization motives and expectations about how immigrants should acculturate in the receiving society (i.e., acculturation orientations). Our findings provide evidence for both processes of political absorption and transformation. On the one hand, belongingness motives underlying naturalization were connected to orientations towards host culture adoption, which in turn predicted support for restrictive immigration policies. On the other hand, instrumental motives were connected to orientations towards heritage culture maintenance, which in turn predicted support for permissive immigration policies. To conclude, we discuss the social psychological dynamics involved in the transition from national outsiders to national insiders and highlight the effects of naturalization on power relations between national majority and immigrant minority groups.     

Authoritarianism as a personality trait: Evidence from a longitudinal behavior genetic study

Authoritarianism has long been conceived of as a highly stable personality trait ( and ), though recent accounts have argued that authoritarianism is too malleable to justify this conception. We provided a test of the trait conception of authoritarianism by measuring its stability in a community sample of twins over a 15 year period, and by identifying the source of any stability with biometric modeling. Our results showed that authoritarianism exhibited a high degree of rank-order stability (r = .74). Biometric analyses indicated that this stability derived primarily from genetic influences, with changes in authoritarianism due to the unique experiences of the individual. In both of these respects, our results were highly comparable to those reported for other personality traits in previous work, indicating support for the trait conception of authoritarianism. Other results of note included a higher degree of stability among the more educated portion of the sample, supporting a hypothesis by Krosnick and Alwin (1989).     

Genetic Support for the Dual Nature of Attention Deficit Hyperactivity Disorder: Substantial Genetic Overlap Between the Inattentive and Hyperactive–impulsive Components

Objective Attention deficit hyperactivity disorder (ADHD) is a common, complex and highly heritable disorder, characterised by inattentive, impulsive and overactive behaviour. Evidence for the heritability of ADHD measures in twin population samples has come from the analysis of total scores that combine inattentive and hyperactive–impulsive symptoms subscales. This study investigated, in a community sample, the aetiology of ADHD-like traits and the aetiological overlap between the two dimensions that define the ADHD disorder. Materials and Methods Parents of 6,222 approximately 8-year-old twin pairs from the Twins Early Development Study (TEDS) population sample completed the two subscales of the Conners’ 18-item DSMIV checklist, a screening instrument for ADHD symptoms. Results Both subscales were highly heritable (hyperactive–impulsive: 88%; inattentive: 79%). Bivariate genetic modelling indicated substantial genetic overlap between the two components; however, there were significant independent genetic effects. Conclusions These findings suggest that many genes associated with the hyperactivity–impulsivity dimension will also be associated with the inattentive dimension but that there is significant genetic heterogeneity as well. These results provide genetic support for combining the two behavioural dimensions that define ADHD, but also suggest that some symptom-specific genes will also be identified. Correspondence and reprint requests to Gráinne McLoughlin, SGDP Centre, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, Tel: +44(0) 207-848-5261; Email: g.mcloughlin@iop.kcl.ac.uk.     

Morality and political orientations: An analysis of their relationship

Groups are social constructions with differences. People spontaneously attempt to explain differences between groups. Stereotypes often play this explanatory role. Specifically, group members tend to attribute different essences to social categories. Given widespread ethnocentrism, it is not surprising that individuals reserve “the human essence” for their ingroup, while other groups are attributed a lesser humanity. This phenomenon is called infra‐humanisation and happens outside people's awareness. Secondary emotions (e.g., love, hope, contempt, resentment) are considered uniquely human emotions in contrast to primary emotions (e.g., joy, surprise, fear, anger) that are shared with animals. The research programme summarised in this chapter demonstrates through various paradigms that members of groups not only attribute more secondary emotions to their ingroup than to outgroups, but are also reluctant to associate these emotions with outgroups. Moreover, people behave less cooperatively with an outgroup member who expresses himself with secondary emotions than with an ingroup member who uses the same terms. Interestingly, infra‐humanisation occurs for both high‐ and low‐status groups, even in the absence of conflict between groups.