The genetics of politics: discovery, challenges, and progress

Political efficacy and fertility intentions: A survey experiment study in Hong Kong, Taiwan, and Singapore

The decline in fertility is a pressing issue for most advanced economies. Previous studies on fertility have not paid enough attention to politics. This study investigates the role of political efficacy on people's fertility intentions in Hong Kong, Taiwan and Singapore - three advanced economies with different political regimes. We also uncover how such a relationship varies depending on people's political attitudes. This study gathered data from three online surveys with a factorial experiment design in Hong Kong (N = 1895), Taiwan (N = 1971), and Singapore (N = 1985). The results of random-intercept regression analyses show that the impact of political efficacy varies depending on the context. The results indicate that political efficacy positively impacts fertility intentions in Hong Kong and Taiwan, where there are active political movements, especially among those who support democratic values. In Singapore, where there is a lack of active political movements, political efficacy has a lesser impact on fertility intentions. In modern societies with advanced economies and influential political voices from civil society, promoting citizens' involvement in policymaking may be a beneficial strategy to increase fertility rates.

The reductionism of genopolitics in the context of the relationships between biology and political science

The past two decades have seen an increase in the use of theories, data, assumptions and methods of the biological sciences in studying political phenomena. One of the approaches that combine biology with political science is genopolitics. The goal of the study was to analyse the basic ontological, methodological and epistemological assumptions for the reductionism of genopolitics. The results show that genopolitics assumes methodological reductionism but rejects ontological and epistemological reductionism. The key consequences of the findings are the irreducibility of political science to biology and the complementarity of genopolitical explanations and political science explanations based on culturalism. If my findings prove to be correct, they give rise to the formation of a hypothesis regarding the anti-reductionist orientation of the contemporary links between political science and biology. An important step towards confirming or falsifying such a hypothesis will be exploring the reductionism of contemporary biopolitical approaches such as neuropolitics or evolutionary political psychology.

Afraid of whom?: Threat sensitivity's influence changes with perceived source of threat

Taking insights from the fields of psychology and biology, a growing body of scholarship considers the psychophysiological foundations of political attitudes. Subconscious emotional reactions to threat, for example, have been shown to predict socially conservative attitudes toward out-groups. However, many of these studies fail to consider different sources of perceived threat. Using a combination of survey and physiological data, I distinguish between fear of others and fear of authority, finding that threat sensitivity predicts divergent political attitudes depending on the strength of each. Those who are more sensitive to threat from others tend to hold socially conservative attitudes, while those who fear authority generally take more libertarian positions. As sensitivity to threat is at least partially inherited, these findings highlight the genetic role of political predispositions.

It takes guts to be a rebel! A dynamic coordination account of the relationship between motivational reactivity, social morality, and political ideology

This study tests two sets of competing hypotheses about the relationship between trait reactivity to positive and negative stimuli (i.e., motivational reactivity), moral stances on social principles (i.e., social morality), and political ideology. The classic view contends that a specific political ideology or social morality results from a specific motivational reactivity pattern, whereas the dynamic coordination account suggests that trait motivational reactivity modulates an individual's political ideology and social morality as a result of the majority political beliefs in their immediate social context. A survey using subjects recruited from a liberal-leaning social context was conducted to test these hypotheses. Results support the dynamic coordination account. Reactivity to negativity (indexed by defensive system activation scores) is associated with the adoption of the dominant social morality and political ideology. Reactivity to positivity (indexed by appetitive system activation scores) is associated with the adoption of nondominant social moral and political stances.

Youth’s own political interest can explain their political interactions with important others

This study examines the idea that youth’s perceptions of their political interactions with important others are influenced by their own political interest to a greater extent than the perceived political interactions that influence youth’s political interest. Hence, it was proposed that youth’s perceptions of important others’ (parents’, teachers’, friends’) political views, political interest, political influence, and support, as well as of being susceptible to others’ political communication, are all affected by their own political interest. Community samples of 908 13-year-olds and 869 16-year-olds were followed over 1 year. Latent change models supported the idea that youth’s political interest significantly affected their perceptions of important others’ political views, influence, and support over time in both cohorts. In 11 out of 12 longitudinal analyses, youth’s political interest strongly affected perceptions of their political interactions with others, but none of the 12 analyses showed that the perceptions of political interactions with others strongly predicted a change in youth’s political interest. These results suggest that the political interest of young people is an input in their political development, making politically interested youth active agents in their political interactions with their important others.

People's desire to be in nature and how they experience it are partially heritable

Nature experiences have been linked to mental and physical health. Despite the importance of understanding what determines individual variation in nature experience, the role of genes has been overlooked. Here, using a twin design (TwinsUK, number of individuals = 2,306), we investigate the genetic and environmental contributions to a person's nature orientation, opportunity (living in less urbanized areas), and different dimensions of nature experience (frequency and duration of public nature space visits and frequency and duration of garden visits). We estimate moderate heritability of nature orientation (46%) and nature experiences (48% for frequency of public nature space visits, 34% for frequency of garden visits, and 38% for duration of garden visits) and show their genetic components partially overlap. We also find that the environmental influences on nature experiences are moderated by the level of urbanization of the home district. Our study demonstrates genetic contributions to individuals' nature experiences, opening a new dimension for the study of human-nature interactions.

Idealisation, genetic explanations and political behaviours: Notes on the anti-reductionist critique of genopolitics

The rapid development of genetic research, determined, among others, by the requirements of The Human Genome Project, and a gradual reorientation in the perception of the role of nature and culture in the process of shaping complex networks of human relations by some political scientists, result in the increasing application of genetic data and methods in research regarding political behaviours. One of the key philosophical objections against the studies of the genetic foundations of political behaviours is that of excessive reductionism. This is supposed to manifest itself in the inadequate selection of the level of analysis for the explained phenomenon, the incompleteness of explanations and their low utility. My findings show that this objection is not sufficiently supported by contemporary science. Both studies using classical behavioural genetic methodologies and studies using DNA-based methods show that genes most likely play a role in political behaviours. Emphasising the significance of genetic influences in the midst of multiple extra-genetic interactions generates highly idealised explanations. Using the conceptual apparatus of the deformational concept of culture, I have demonstrated that the omission of a number of important extra-genetic influences by researchers is a consequence of focusing on specific causal patterns. This omission, however, does not entail negating the influence of non-genetic factors and, importantly, it may not have to be permanent. Following this approach, if correct, the reductionism of research into the genetic foundations of political behaviours is a standard cognitive procedure applied in science.

A neurocognitive model of ideological thinking

Ideological behavior has traditionally been viewed as a product of social forces. Nonetheless, an emerging science suggests that ideological worldviews can also be understood in terms of neural and cognitive principles. The article proposes a neurocognitive model of ideological thinking, arguing that ideological worldviews may be manifestations of individuals' perceptual and cognitive systems. This model makes two claims. First, there are neurocognitive antecedents to ideological thinking: the brain's low-level neurocognitive dispositions influence its receptivity to ideological doctrines. Second, there are neurocognitive consequences to ideological engagement: strong exposure and adherence to ideological doctrines can shape perceptual and cognitive systems. This article details the neurocognitive model of ideological thinking and synthesizes the empirical evidence in support of its claims. The model postulates that there are bidirectional processes between the brain and the ideological environment, and so it can address the roles of situational and motivational factors in ideologically motivated action. This endeavor highlights that an interdisciplinary neurocognitive approach to ideologies can facilitate biologically informed accounts of the ideological brain and thus reveal who is most susceptible to extreme and authoritarian ideologies. By investigating the relationships between low-level perceptual processes and high-level ideological attitudes, we can develop a better grasp of our collective history as well as the mechanisms that may structure our political futures.

Ethnic Identity and Genome Wide Runs of Homozygosity

It is long known that inbreeding increases the detrimental effects of recessive sequence variants in "Runs of Homozygosity" (ROHs). However, although the phenotypic association of ROH has been investigated for a variety of traits, the statistical power of the results often remains limited as a sufficiently high number of cases are available for only a restricted number of traits. In the present study, we aim to analyze the association of runs of homozygosity with the trait "in-group ethnic favoritism". This analysis assumes that if ethnic identity is important for an individual, that individual may tend to marry more frequently within their own group and therefore ROH are expected to increase. We hypothesize that an attitude preferring one's own ethnic group may be associated with a stronger tendency of inbreeding and, as a result, with more and longer ROHs. Accordingly, we investigated the association between the attitude to someone's own ethnicity and ROH, using the Wisconsin Longitudinal data (WLS, total N ~ 9000) as discovery data set and the Brisbane Twin data as replication data set (N ~ 8000). We find that both the number as well as the total length of homozygous segments are significantly positively associated with "in-group ethnic favoritism", independent of the method used for ROH calculation.

Evaluating Belief System Networks as a Theory of Political Belief System Dynamics

A theory of political belief system dynamics should incorporate causal connections between elements of the belief system and the possibility that belief systems are influenced by exogenous factors. These necessary components can be satisfied by conceptualizing an individual's belief system as a network of causally connected attitudes and identities which, via the interactions between the elements and the push of exogenous influences, produces the disparate phenomena in the belief systems literature. We implement this belief systems as networks theory in a dynamic Ising model and demonstrate that the theory can integrate at least six otherwise unrelated phenomenon in the political belief systems literature, including work on attitude consistency, cross-pressures, spillover effects, partisan cues, and ideological differences in attitude consensus. Our findings suggest that belief systems are not just one thing, but emerge from the interactions between the attitudes and identities in the belief system. All code is available: https://osf.io/aswy8/?view_only=99aff77909094bddabb5d382f6db2622.

Factors affecting attitudes toward migrants-An evolutionary approach

OBJECTIVE

To understand migration from an evolutionary perspective, this phenomenon has so far been mainly investigated in animal species. We therefore aim to investigate the potential evolutionary roots of attitudes toward migrants in humans.

METHODS

We used data from the European Social Survey (n = 83 734), analyzing attitudes toward migrants by performing ordinal mixed models.

RESULTS

We found that men have a more restrictive attitude toward migration than women, which increases with age and is stronger with a child in the household. Attitude toward migrants is also more skeptical if migrants have a different ethnicity and are from poorer countries. Increasing education and religiousness are associated with a more positive attitude toward migrants, particularly toward migrants of different ethnicity and from poorer countries.

DISCUSSION

Although migration flows are a hallmark of the human species, previous findings suggest that (pre-)historic migration flows were at times accompanied by conflict and violence, while at the same time, they insured survival by allowing cultural exchange and the avoidance of inbreeding. Accordingly, we assume that contemporary attitudes toward migration are rooted in our evolutionary past. We discuss the respective behavioral patterns from an evolutionary perspective, arguing that both-a negative attitude as well as openness-make sense.

Culture, institutions and democratization

We construct a model of revolution and transition to democracy under individualistic and collectivist cultures. The main result is that, despite facing potentially more challenging collective action problems, countries with individualistic cultures are more likely to end up adopting democracy earlier than countries with collectivist cultures. Our empirical analysis suggests a strong and robust association between individualistic cultures and average polity scores and durations of democracy, even after controlling for other determinants of democracy emphasized in the literature. We provide evidence that countries with collectivist cultures also are more likely to experience autocratic breakdowns and transitions from autocracy to autocracy.

Dispositional Fear and Political Attitudes

Previous work proposes that dispositional fear exists predominantly among political conservatives, generating the appearance that fears align strictly along party lines. This view obscures evolutionary dynamics because fear evolved to protect against myriad threats, not merely those in the political realm. We suggest prior work in this area has been biased by selection on the dependent variable, resulting from an examination of exclusively politically oriented fears that privilege conservative values. Because the adaptation regulating fear should be based upon both universal and ancestral-specific selection pressures combined with developmental and individual differences, the elicitation of it should prove variable across the ideological continuum dependent upon specific combinations of fear and value domains. In a sample of ~ 1,600 Australians assessed with a subset of the Fear Survey Schedule II, we find fears not infused with political content are differentially influential across the political spectrum. Specifically, those who are more fearful of sharp objects, graveyards, and urinating in public are more socially conservative and less supportive of gay rights. Those who are more fearful of death are more supportive of gay rights. Those who are more fearful of suffocating and swimming alone are more concerned about emissions controls and immigration, while those who are more fearful of thunderstorms are also more anti-immigration. Contrary to existing research, both liberals and conservatives are more fearful of different circumstances, and the role of dispositional fears are attitude-specific.

An Experimental Examination of Demand-Side Preferences for Female and Male National Leaders

Females constitute a far smaller proportion of political leaders than their proportion in the general population. Leading demand- and supply side explanations for this phenomenon account for some of the variance but leave a great deal unexplained. In an effort to account for additional variance, this research evaluates the issue informed by the biological theory of evolution by natural selection, a foundational explanation for the diversity and function of living organisms. It experimentally assesses how varying types of inter- and intragroup threat-a recurring ancestral problem-affect demand for female and male national leaders. This work analyzes data collected from individuals (N = 826) in the U.S. during the 2012 Cooperative Congressional Election Study. The results suggest the predominant preference for male over female leaders in some contexts may be the non-adaptive and non-functional but lingering outcome of an adaptive preference for physically formidable allies that was shaped by natural selection in ancestral environments.

Individual differences in trust evaluations are shaped mostly by environments, not genes

People evaluate a stranger's trustworthiness from their facial features in a fraction of a second, despite common advice "not to judge a book by its cover." Evaluations of trustworthiness have critical and widespread social impact, predicting financial lending, mate selection, and even criminal justice outcomes. Consequently, understanding how people perceive trustworthiness from faces has been a major focus of scientific inquiry, and detailed models explain how consensus impressions of trustworthiness are driven by facial attributes. However, facial impression models do not consider variation between observers. Here, we develop a sensitive test of trustworthiness evaluation and use it to document substantial, stable individual differences in trustworthiness impressions. Via a twin study, we show that these individual differences are largely shaped by variation in personal experience, rather than genes or shared environments. Finally, using multivariate twin modeling, we show that variation in trustworthiness evaluation is specific, dissociating from other key facial evaluations of dominance and attractiveness. Our finding that variation in facial trustworthiness evaluation is driven mostly by personal experience represents a rare example of a core social perceptual capacity being predominantly shaped by a person's unique environment. Notably, it stands in sharp contrast to variation in facial recognition ability, which is driven mostly by genes. Our study provides insights into the development of the social brain, offers a different perspective on disagreement in trust in wider society, and motivates new research into the origins and potential malleability of face evaluation, a critical aspect of human social cognition.

What determines perceived income justice? Evidence from the German TwinLife study

Whether individuals perceive their income as being fair has far-reaching consequences in the labor market and beyond. Yet we know little about the determinants of variation in perceived income justice across individuals. In this paper, we ask to what extent differences in genes are related to variation in individuals' perceived income justice, and whether there is a gene-environment component. Analyzing data from the German TwinLife study, we find that more than 30% of individuals' perceived income justice can be attributed to genes. The rest is mostly related to an idiosyncratic environment.

Genetic correlates of social stratification in Great Britain

Human DNA polymorphisms vary across geographic regions, with the most commonly observed variation reflecting distant ancestry differences. Here we investigate the geographic clustering of common genetic variants that influence complex traits in a sample of ~450,000 individuals from Great Britain. Of 33 traits analysed, 21 showed significant geographic clustering at the genetic level after controlling for ancestry, probably reflecting migration driven by socioeconomic status (SES). Alleles associated with educational attainment (EA) showed the most clustering, with EA-decreasing alleles clustering in lower SES areas such as coal mining areas. Individuals who leave coal mining areas carry more EA-increasing alleles on average than those in the rest of Great Britain. The level of geographic clustering is correlated with genetic associations between complex traits and regional measures of SES, health and cultural outcomes. Our results are consistent with the hypothesis that social stratification leaves visible marks in geographic arrangements of common allele frequencies and gene-environment correlations.

Political Attitude and Fertility: Is There a Selection for the Political Extreme?

There is growing evidence that human ideology as well as social and political attitudes also have a genetic basis. In case of some genetic predisposition of political attitude, an association with fertility would be a hint of potential selection on political ideology. We therefore investigated on the basis of men and women that have completed, respectively, almost completed reproduction, of three different data sets (the World Value Survey 1981-2014 covering a wide range of countries and developmental levels, n = 152,380, the Survey of Health, Ageing and Retirement in Europe of 2005, n = 65,912, and the General Social Survey of the United States 1972-2014, n ∼ 6200) whether political attitude is associated with number of children. Overall, in the world wide survey, both extreme political attitudes, albeit more pronounced for right/conservative than for left/liberal attitude, are associated with higher average offspring number compared to intermediate attitudes. If countries are analyzed separately, however, the picture is inconsistent, and in most countries, the association is non-significant. In the European and the US-survey, only the political right is associated with above average number of children. The time series of US data from 1972 to 2014 shows that at least in the US-sample, this pattern emerged during the 1990s: in the 1970s and 1980s, also in the US-sample both political extremes had a reproductive advantage, which vanished for left wing individuals during the 1990s. From an evolutionary perspective, we are not able to draw final conclusions as the association between political attitude and reproduction varies across countries and time. Nonetheless, the overall pattern suggests that in human evolutionary history, both left and right political attitudes may have conveyed fitness benefits so that both attitudes have been kept in the population.

On the genetic and environmental sources of social and political participation in adolescence and early adulthood

Political participation (POP), social participation (SOP), and political interest (PI) are important indicators of social status and social inequality. Previous studies on related trait differences yielded genetic and environmental contributions. However, focusing on adult samples, classical twin designs, and convenience samples often restricts parameter estimation and generalizability, and limits the understanding of age differences. We investigated sources of variance in POP, SOP, and PI in late adolescence and early adulthood with an extended twin family design (ETFD). We analyzed data from over 2,000 representative German twin families. Individual environments not shared by family members reflected the major source of variance for all variables, but genetic influences were also pronounced. Genetic effects were mostly higher for young adults, whereas effects of twins' shared environment were significant in adolescence. Our study deepens the understanding of the interplay between genetic and environmental factors in shaping differences in young persons' integration in society.

Psychopathy to Altruism: Neurobiology of the Selfish-Selfless Spectrum

The age-old philosophical, biological, and social debate over the basic nature of humans as being “universally selfish” or “universally good” continues today highlighting sharply divergent views of natural social order. Here we analyze advances in biology, genetics and neuroscience increasing our understanding of the evolution, features and neurocircuitry of the human brain underlying behavior in the selfish–selfless spectrum. First, we examine evolutionary pressures for selection of altruistic traits in species with protracted periods of dependence on parents and communities for subsistence and acquisition of learned behaviors. Evidence supporting the concept that altruistic potential is a common feature in human populations is developed. To go into greater depth in assessing critical features of the social brain, the two extremes of selfish–selfless behavior, callous unemotional psychopaths and zealous altruists who take extreme measures to help others, are compared on behavioral traits, structural/functional neural features, and the relative contributions of genetic inheritance versus acquired cognitive learning to their mindsets. Evidence from population groups ranging from newborns, adopted children, incarcerated juveniles, twins and mindfulness meditators point to the important role of neuroplasticity and the dopaminergic reward systems in forming and reforming neural circuitry in response to personal experience and cultural influences in determining behavior in the selfish–selfless spectrum. The underlying neural circuitry differs between psychopaths and altruists with emotional processing being profoundly muted in psychopaths and significantly enhanced in altruists. But both groups are characterized by the reward system of the brain shaping behavior. Instead of rigid assignment of human nature as being “universally selfish” or “universally good,” both characterizations are partial truths based on the segments of the selfish–selfless spectrum being examined. In addition, individuals and populations can shift in the behavioral spectrum in response to cognitive therapy and social and cultural experience, and approaches such as mindfulness training for introspection and reward-activating compassion are entering the mainstream of clinical care for managing pain, depression, and stress.

To Go Forward, We Must Look Back: The Importance of Evolutionary Psychology for Understanding Modern Politics

As new waves of populism arise and cause disruption around the globe, there is both great interest in attempting to explain the origin of this dynamic as well as a need to ameliorate its potentially destructive impact. Perhaps the greatest signal of seismic change is the global dismantling of American institutional control of the postwar world following the election of Donald Trump in the United States. In the wake of such dramatic changes, it may seem odd to turn to evolutionary psychology which looks deeply into the past to try to understand current events, but, in fact, modern technology has dramatically changed the shape of political communication in just such a way as to make politics more personal once again, increasing the need to understand and interpret modern politics through an evolutionary lens. In fact, current modern political turmoils demonstrate how important evolutionary themes are and how critical they remain to understand how current forms of populism tape into older tribal sentiments and drives. Modern technology allows for a form of interpretative politics that no longer need to be mediated by political institutions or larger social structures, including enduring ones such as marriage. Indeed, in any ways, as we have technologically advanced, we have also regressed to more immediate, emotional, and personal forms of political communication. And it is only in understanding the nature of that personal political psychology that we can begin to grapple seriously with the challenges of today, including the consequences of global populism.

Influence of authoritarianism, vagal tone and mental fatigue on obedience to authority

Recent research suggests that obedience in the Milgram paradigm is underpinned by stress vulnerability and inhibitory control over pain sharing. Because self-regulatory fatigue (SRF) induction is a suited method to investigate the influence of inhibitory control on behaviour, participants (n = 99) were randomly assigned to a High vs. Low self-regulatory condition. Heart rate variability (HRV, a biomarker of stress vulnerability) was collected during 5-min baseline and continuously during the experimental procedure. Prior to the experiment, participants completed an online survey assessing right-wing authoritarianism (RWA), a well-known predictor of obedience. Using the Immersive Video Milgram Obedience Experiment, we found (i) that lower resting HRV predicted higher destructive obedience, (ii) that low self-regulatory inhibition (induced by fatigue) reduced destructive obedience, (iii) that the well-established influence of RWA on destructive obedience was suppressed in the presence of SRF. Implications for future directions in obedience research are discussed.

Coalitional rivalry may hurt in economic exchanges such as trade but help in war

Economic exchange constitutes the basis of many, but not all, aspects of human cooperation. The incentives overlap with, but remain distinct in important ways, from other fundamental aspects of cooperation, including the organization of collective violence for combat. The specific alignment of sometimes-conflicting goals helps inform the construction of political ideology.

The political reference point: How geography shapes political identity

It is commonly assumed that how individuals identify on the political spectrum–whether liberal, conservative, or moderate–has a universal meaning when it comes to policy stances and voting behavior. But, does political identity mean the same thing from place to place? Using data collected from across the U.S. we find that even when people share the same political identity, those in “bluer” locations are more likely to support left-leaning policies and vote for Democratic candidates than those in “redder” locations. Because the meaning of political identity is inconsistent across locations, individuals who share the same political identity sometimes espouse opposing policy stances. Meanwhile, those with opposing identities sometimes endorse identical policy stances. Such findings suggest that researchers, campaigners, and pollsters must use caution when extrapolating policy preferences and voting behavior from political identity, and that animosity toward the other end of the political spectrum is sometimes misplaced.

Issues or Identity? Cognitive Foundations of Voter Choice

Voter choice is one of the most important problems in political science. The most common models assume that voting is a rational choice based on policy positions (e.g., key issues) and nonpolicy information (e.g., social identity, personality). Though such models explain macroscopic features of elections, they also reveal important anomalies that have been resistant to explanation. We argue for a new approach that builds upon recent research in cognitive science and neuroscience; specifically, we contend that policy positions and social identities do not combine in merely an additive manner, but compete to determine voter preferences. This model not only explains several key anomalies in voter choice, but also suggests new directions for research in both political science and cognitive science.

Genes, psychological traits and civic engagement

Civic engagement is a classic example of a collective action problem: while civic participation improves life in the community as a whole, it is individually costly and thus there is an incentive to free ride on the actions of others. Yet, we observe significant inter-individual variation in the degree to which people are in fact civically engaged. Early accounts reconciling the theoretical prediction with empirical reality focused either on variation in individuals' material resources or their attitudes, but recent work has turned to genetic differences between individuals. We show an underlying genetic contribution to an index of civic engagement (0.41), as well as for the individual acts of engagement of volunteering for community or public service activities (0.33), regularly contributing to charitable causes (0.28) and voting in elections (0.27). There are closer genetic relationships between donating and the other two activities; volunteering and voting are not genetically correlated. Further, we show that most of the correlation between civic engagement and both positive emotionality and verbal IQ can be attributed to genes that affect both traits. These results enrich our understanding of the way in which genetic variation may influence the wide range of collective action problems that individuals face in modern community life.

The genetic and environmental foundations of political, psychological, social, and economic behaviors: a panel study of twins and families

Here we introduce the Genetic and Environmental Foundations of Political and Economic Behaviors: A Panel Study of Twins and Families (PIs Alford, Hatemi, Hibbing, Martin, and Smith). This study was designed to explore the genetic and environmental influences on social, economic, and political behaviors and attitudes. It involves identifying the psychological mechanisms that operate on these traits, the heritability of complex economic and political traits under varying conditions, and specific genetic correlates of attitudes and behaviors. In addition to describing the study, we conduct novel analyses on the data, estimating the heritability of two traits so far unexplored in the extant literature: Machiavellianism and Baron-Cohen's Empathizing Quotient.

Human kin detection

Natural selection has favored the evolution of behaviors that benefit not only one's genes, but also their copies in genetically related individuals. These behaviors include optimal outbreeding (choosing a mate that is neither too closely related, nor too distant), nepotism (helping kin), and spite (hurting non-kin at a personal cost), and all require some form of kin detection or kin recognition. Yet, kinship cannot be assessed directly; human kin detection relies on heuristic cues that take into account individuals' context (whether they were reared by our mother, or grew up in our home, or were given birth by our spouse), appearance (whether they smell or look like us), and ability to arouse certain feelings (whether we feel emotionally close to them). The uncertainties of kin detection, along with its dependence on social information, create ample opportunities for the evolution of deception and self-deception. For example, babies carry no unequivocal stamp of their biological father, but across cultures they are passionately claimed to resemble their mother's spouse; to the same effect, 'neutral' observers are greatly influenced by belief in relatedness when judging resemblance between strangers. Still, paternity uncertainty profoundly shapes human relationships, reducing not only the investment contributed by paternal versus maternal kin, but also prosocial behavior between individuals who are related through one or more males rather than females alone. Because of its relevance to racial discrimination and political preferences, the evolutionary pressure to prefer kin to non-kin has a manifold influence on society at large.

Like parent, like child? Development of prejudice and tolerance towards immigrants

Although intergroup attitudes are assumed to develop due to the influence of parents, there is no longitudinal evidence supporting this claim. In addition, research on socialization of intergroup attitudes has omitted possible effects of adolescents on their parents. We also know little about the conditions under which intergroup attitudes are transmitted. This two-wave, 2 years apart, study of adolescents (N = 507) and their parents examined the relations between parents and adolescents' prejudice and tolerance from a longitudinal perspective. The study tested whether parental prejudice and tolerance would predict over-time changes in adolescents' attitudes and whether adolescents' prejudice and tolerance would elicit changes in parental attitudes. Additionally, it explored whether some of the effects would depend on perceived parental support. Results showed significant bidirectional influences between parents and adolescents' attitudes. In addition, adolescents who perceived their parents as supportive showed higher parent-adolescent correspondence in prejudice than youth with low parental support. These findings show that intergroup attitudes develop as a result of mutual influences between parents and adolescents. Hence, the unidirectional transmission model and previous research findings should be revisited. The results also suggest that parents' prejudice influence adolescents' attitudes to the extent that youth perceive their parents as supportive.

Normative seeds for deadly martyrdoms

Even if Lankford's biographical examination of perpetrators of suicidal attacks serves to alert us on the role played by individual factors in their recruitment, psychological frailties, distress, or coercion do not exhaust the causal pathways to deadly martyrdom. Normative personality attributes must be explored further in order to ascertain plausible roots of murderous sacrifice. We have advanced (Tobeña 2004b; 2009; 2011) a template of normative temperamental traits that could lead activists to the threshold of volunteering for murderous missions.

Genetic influences on political ideologies: twin analyses of 19 measures of political ideologies from five democracies and genome-wide findings from three populations

Almost 40 years ago, evidence from large studies of adult twins and their relatives suggested that between 30 and 60% of the variance in social and political attitudes could be explained by genetic influences. However, these findings have not been widely accepted or incorporated into the dominant paradigms that explain the etiology of political ideology. This has been attributed in part to measurement and sample limitations, as well the relative absence of molecular genetic studies. Here we present results from original analyses of a combined sample of over 12,000 twins pairs, ascertained from nine different studies conducted in five democracies, sampled over the course of four decades. We provide evidence that genetic factors play a role in the formation of political ideology, regardless of how ideology is measured, the era, or the population sampled. The only exception is a question that explicitly uses the phrase "Left-Right". We then present results from one of the first genome-wide association studies on political ideology using data from three samples: a 1990 Australian sample involving 6,894 individuals from 3,516 families; a 2008 Australian sample of 1,160 related individuals from 635 families and a 2010 Swedish sample involving 3,334 individuals from 2,607 families. No polymorphisms reached genome-wide significance in the meta-analysis. The combined evidence suggests that political ideology constitutes a fundamental aspect of one's genetically informed psychological disposition, but as Fisher proposed long ago, genetic influences on complex traits will be composed of thousands of markers of very small effects and it will require extremely large samples to have enough power in order to identify specific polymorphisms related to complex social traits.

The Influence of Major Life Events on Economic Attitudes in a World of Gene-Environment Interplay

The role of "genes" on political attitudes has gained attention across disciplines. However, person-specific experiences have yet to be incorporated into models that consider genetic influences. Relying on a gene-environment interplay approach, this study explicates how life-events, such as losing one's job or suffering a financial loss, influence economic policy attitudes. The results indicate genetic and environmental variance on support for unions, immigration, capitalism, socialism and property tax is moderated by financial risks. Changes in the magnitude of genetic influences, however, are temporary. After two years, the phenotypic effects of the life events remain on most attitudes, but changes in the sources of individual differences do not. Univariate twin models that estimate the independent contributions of genes and environment on the variation of attitudes appear to provide robust baseline indicators of sources of individual differences. These estimates, however, are not event or day specific. In this way, genetic influences add stability, while environment cues change, and this process is continually updated.

Gene-Environment Interplay in Twin Models

In this article, we respond to Shultziner's critique that argues that identical twins are more alike not because of genetic similarity, but because they select into more similar environments and respond to stimuli in comparable ways, and that these effects bias twin model estimates to such an extent that they are invalid. The essay further argues that the theory and methods that undergird twin models, as well as the empirical studies which rely upon them, are unaware of these potential biases. We correct this and other misunderstandings in the essay and find that gene-environment (GE) interplay is a well-articulated concept in behavior genetics and political science, operationalized as gene-environment correlation and gene-environment interaction. Both are incorporated into interpretations of the classical twin design (CTD) and estimated in numerous empirical studies through extensions of the CTD. We then conduct simulations to quantify the influence of GE interplay on estimates from the CTD. Due to the criticism's mischaracterization of the CTD and GE interplay, combined with the absence of any empirical evidence to counter what is presented in the extant literature and this article, we conclude that the critique does not enhance our understanding of the processes that drive political traits, genetic or otherwise.

Ethical, legal, social, and policy implications of behavioral genetics

The field of behavioral genetics has engendered a host of moral and social concerns virtually since its inception. The policy implications of a genetic basis for behaviors are widespread and extend beyond the clinic to the socially important realms of education, criminal justice, childbearing, and child rearing. The development of new techniques and analytic approaches, including whole-genome sequencing, noninvasive prenatal genetic testing, and optogenetics, has clearly changed the study of behavioral genetics. However, the social context of biomedical research has also changed profoundly over the past few decades, and in ways that are especially relevant to behavioral genetics. The ever-widening scope of behavioral genetics raises ethical, legal, social, and policy issues in the potential new applications to criminal justice, education, the military, and reproduction. These issues are especially critical to address because of their potentially disproportionate effects on vulnerable populations such as children, the unborn, and the incarcerated.

Reflections on Twin Relationships: Twins Reared Apart and Twins of Opposite Sex / Research Reviews: Second Language Acquisition; Twin Research on Political Behavior; Twinning Rate in Cândido Godói / Human Interest: Twin ‘Cousins’ Separated at Birth; Chinese Quadruplets; Genetic Testing; KÀ (Cirque du Soleil)

The complexities of twin relationships posed by separate rearing and by opposite sex are considered. Unusual cases may highlight unique social-interactional processes and outcomes occurring in these pairs. Research reviews include recent twin studies on second language acquisition, political behavior, and multiple birth rates. Items of more general interest include twin ‘cousins’ reared apart, indistinguishable monozygotic quadruplets, a genetic testing dilemma, and a performance about separated twins.