Nature-nurture interplay: genetically informative designs contribute to understanding the effects of trauma and interpersonal violence

The past two decades have seen an explosion in research in the fields of violence and trauma and behavior genetics. These two fields came into direct conflict when Lisabeth Fisher DiLalla and Irving I. Gottesman outlined a fundamental conceptual limitation of trauma and violence research: that rather than being causal, the well-documented relationship between exposure to trauma or violence and later negative outcomes could be explained by gene-environment correlation. In the past decade, researchers have addressed this limitation by studying the effects of trauma and violence using genetically informative designs. This report briefly discusses the gains made from this research approach and the promising future for genetically informative trauma and violence research.

Genetic and environmental contributions to pro-social attitudes: a twin study of social responsibility

Although 51 twin and adoption studies have been performed on the genetic architecture of antisocial behaviour, only four previous studies have examined a genetic contribution to pro-social behaviour. Earlier work by the author with the University of London Institute of Psychiatry Adult Twin Register found that genes contributed approximately half of the variance to measures of self-report altruism, empathy, nurturance and aggression, including acts of violence. The present study extends those results by using a 22-item Social Responsibility Questionnaire with 174 pairs of monozygotic twins and 148 pairs of dizygotic twins. Forty-two per cent of the reliable variance was due to the twins' genes, 23% to the twins' common environment and the remainder to the twins' non-shared environment.

Behavioral genetics of personality

Behavioral genetic personality research has moved from findings of genetic and environmental effects to new areas. Personality disorders have been included, children and adolescents studied, gender effects evaluated, and the importance of rater sources investigated. Recently, multivariate methods have been applied to disentangle the genetic and environmental latent structure, and investigate covariance in mental disorders. Perhaps the most exciting recent developments are the investigations of situation variables, the studies of how genotypes influence how individuals select themselves into situations and other form of gene-environment correlations, and how genotype moderates the effect of situations and circumstances on behavior (gene-environment interaction). In the future, we will learn how personality, partly determined by heredity, influences our entire lives. We will better understand what we experience, how we interpret the experiences and how to react to them effectively. We will learn how our mental lives develop while we interact with the environment, and we will broaden our understanding of which genes are coding for mental health and mental disorders.

Genetic and Environmental Influences on Antisocial Behaviors: Evidence from Behavioral–Genetic Research

This article reviews behavioral-genetic research into human antisocial behavior. The focus is on studies of antisocial behavior that have been leading the way in investigating environmental and genetic influences on human behavior. The first generation of studies, which provided quantitative estimates attesting that genes and environments each influence about half of the population's variation in antisocial behaviors is interpreted. Then how behavioral-genetic methods are being applied to test developmental theory and to detect environmental causes of antisocial behavior is illustrated. Evidence for interactions between genes and the environment in the etiology of antisocial behavior is also examined. The article ends by envisioning future work on gene-environment interplay in the etiology of antisocial behavior.

In the eye of the storm: Race and genomics in research and practice

The difficulties of operationalizing race in research and practice for social, behavioral, and genetic researchers and practitioners are neither new nor related to recent genetic knowledge. For geneticists, the bases for understanding groups are clines, observed traits that gradually change in frequency between geographic regions without distinct identifiable population boundaries and population histories that carry information about the distribution of genetic variants. For psychologists, race may not exist or be a social and cultural construct associated with fluid social inferences. Because definitions of populations and race can be socially and biologically incongruent, the authors suggest that geneticists and social and behavioral scientists and clinicians attend to external validity issues by operationalizing population and racial categories and avoiding race proxies for other biological, social, and cultural constructs in research designs, data analyses, and clinical practice.

Maternal expressed emotion predicts children's antisocial behavior problems: using monozygotic-twin differences to identify environmental effects on behavioral development

If maternal expressed emotion is an environmental risk factor for children's antisocial behavior problems, it should account for behavioral differences between siblings growing up in the same family even after genetic influences on children's behavior problems are taken into account. This hypothesis was tested in the Environmental Risk Longitudinal Twin Study with a nationally representative 1994-1995 birth cohort of twins. The authors interviewed the mothers of 565 five-year-old monozygotic (MZ) twin pairs and established which twin in each family received more negative emotional expression and which twin received more warmth. Within MZ pairs, the twin receiving more maternal negativity and less warmth had more antisocial behavior problems. Qualitative interviews were used to generate hypotheses about why mothers treat their children differently. The results suggest that maternal emotional attitudes toward children may play a causal role in the development of antisocial behavior and illustrate how genetically informative research can inform tests of socialization hypotheses.

Emotional and behavioral problems of children living with drug-abusing fathers: comparisons with children living with alcohol-abusing and non-substance-abusing fathers

Although the effects of paternal alcoholism on the psychosocial adjustment of children are well documented, the impact of fathers' illicit drug abuse on their children is poorly understood. The purpose of this study was to compare the adjustment of children living in families with drug-abusing fathers (n = 40) with that of children with fathers who abused alcohol (n = 40) and children with non-substance-abusing fathers (n = 40). Children with drug-abusing fathers experienced more internalizing and externalizing symptoms than children with alcoholic or non-substance-abusing fathers. Interparental conflict and parenting behavior mediated the relationship between family type and children's adjustment. Interventions to improve fathers' parenting behavior and reduce partner conflict may lead to better adjustment among custodial children of drug-abusing fathers.

Physical Maltreatment Victim to Antisocial Child: Evidence of an Environmentally Mediated Process

The well-documented finding that child physical maltreatment predicts later antisocial behavior has at least 2 explanations: (a). Physical maltreatment causes antisocial behavior, and (b). genetic factors transmitted from parents to children influence the likelihood that parents will be abusive and that children will engage in antisocial behavior. The authors tested these hypotheses in the representative Environmental-Risk cohort of 1116 twin pairs and their families, who were assessed when the twins were 5 and 7 years old. Mothers reported on children's experience of physical maltreatment, and mothers and teachers reported on children's antisocial behavior. The findings support the hypothesis that physical maltreatment plays a causal role in the development of children's antisocial behavior and that preventing maltreatment can prevent its violent sequelae.

A genome-wide screen for genes influencing conduct disorder

While behavioral genetic studies have suggested that childhood conduct disorder is under genetic influence, studies aimed at gene identification are lacking. This study represents the first genome-wide linkage analysis directed toward identifying genes contributing to conduct disorder. Genome screens of retrospectively reported childhood conduct disorder and conduct disorder symptomatology were carried out in the genetically informative adult sample collected as part of the Collaborative Study on the Genetics of Alcoholism (COGA). The results suggest that regions on chromosomes 19 and 2 may contain genes conferring risk to conduct disorder. Interestingly, the same region on chromosome 2 has also been linked to alcohol dependence in this sample. Childhood conduct disorder is known to be associated with the susceptibility for future alcohol problems. Taken together, these findings suggest that some of the genes contributing to alcohol dependence in adulthood may also contribute to conduct disorder in childhood.

Who should fund and control the direction of human behavior genetics? Review of Nuffield Council on Bioethics 2002 report, genetics and human behaviour: the ethical context

In this (Nuffield Council on Bioethics 2002), the third in its series on ethics and related issues in genetics (see also Nuffield Council on Bioethics 1993 and Nuffield Council on Bioethics 1998), the Nuffield Council has focused on four'normal' behaviors; intelligence, personality, antisocial behavior and sexual orientation. This is a narrow range of behaviors and one where their discussion of the potential impact of predictive genetic testing is probably inappropriate. They also take an unduly narrow view of the purposes of behavior genetics in the 21st century. It is not simply to estimate heritability but to understand more about the structure of behavior and the processes which underlie it. Their narrow focus and their negative approach to the history and achievements of genetics is reflected in their less than positive support for future behavior genetic research. Behavior geneticists need to do more to publicize what their field has achieved in order to counter the very extensive antibehavior genetics initiatives which are almost unique in science. At the same time, organizations such as the Nuffield Council need to consider carefully the impact their deliberations may have on research funding.

Strong genetic effects on cross-situational antisocial behaviour among 5-year-old children according to mothers, teachers, examiner-observers, and twins' self-reports

BACKGROUND

Early childhood antisocial behaviour is a strong prognostic indicator for poor adult mental health. Thus, information about its etiology is needed. Genetic etiology is unknown because most research with young children focuses on environmental risk factors, and the few existing studies of young twins used only mothers' reports of behaviour, which may be biased.

METHOD

We investigated genetic influences on antisocial behaviour in a representative-plus-high-risk sample of 1116 pairs of 5-year-old twins using data from four independent sources: mothers, teachers, examiner-observers previously unacquainted with the children, and the children themselves.

RESULTS

Children's antisocial behaviour was reliably measured by all four informants; no bias was detected in mothers', teachers', examiners', or children's reports. Variation in antisocial behaviour that was agreed upon by all informants, and thus was pervasive across settings, was influenced by genetic factors (82%) and experiences specific to each child (18%). Variation in antisocial behaviour that was specific to each informant was meaningful variation, as it was also influenced by genetic factors (from 33% for the children's report to 71% for the teachers' report).

CONCLUSIONS

This study and four others of very young twins show that genetic risks contribute strongly to population variation in antisocial behaviour that emerges in early childhood. In contrast, genetic risk is known to be relatively modest for adolescent antisocial behaviour, suggesting that the early-childhood form has a distinct etiology, particularly if it is pervasive across situations.

Does father absence place daughters at special risk for early sexual activity and teenage pregnancy?

The impact of father absence on early sexual activity and teenage pregnancy was investigated in longitudinal studies in the United States (N = 242) and New Zealand (N = 520), in which community samples of girls were followed prospectively from early in life (5 years) to approximately age 18. Greater exposure to father absence was strongly associated with elevated risk for early sexual activity and adolescent pregnancy. This elevated risk was either not explained (in the US. study) or only partly explained (in the New Zealand study) by familial, ecological, and personal disadvantages associated with father absence. After controlling for covariates, there was stronger and more consistent evidence of effects of father absence on early sexual activity and teenage pregnancy than on other behavioral or mental health problems or academic achievement. Effects of father absence are discussed in terms of life-course adversity, evolutionary psychology, social learning, and behavior genetic models.

A biopsychosocial model of the development of chronic conduct problems in adolescence

A biopsychosocial model of the development of adolescent chronic conduct problems is presented and supported through a review of empirical findings. This model posits that biological dispositions and sociocultural contexts place certain children at risk in early life but that life experiences with parents, peers. and social institutions increment and mediate this risk. A transactional developmental model is best equipped to describe the emergence of chronic antisocial behavior across time. Reciprocal influences among dispositions, contexts, and life experiences lead to recursive iterations across time that exacerbate or diminish antisocial development. Cognitive and emotional processes within the child, including the acquisition of knowledge and social-information-processing patterns, mediate the relation between life experiences and conduct problem outcomes. Implications for prevention research and public policy are noted.

Life with (or without) father: the benefits of living with two biological parents depend on the father's antisocial behavior

The salutary effects of being raised by two married, biological parents depend on the quality of care parents can provide. Using data from an epidemiological sample of 1,116 5-year-old twin pairs and their parents, this study found that the less time fathers lived with their children, the more conduct problems their children had, but only if the fathers engaged in low levels of antisocial behavior. In contrast, when fathers engaged in high levels of antisocial behavior, the more time they lived with their children, the more conduct problems their children had. Behavioral genetic analyses showed that children who resided with antisocial fathers received a "double whammy" of genetic and environmental risk for conduct problems. Marriage may not be the answer to the problems faced by some children living in single-parent families unless their fathers can become reliable sources of emotional and economic support.

Genetic and environmental influences on human psychological differences

Psychological researchers typically distinguish five major domains of individual differences in human behavior: cognitive abilities, personality, social attitudes, psychological interests, and psychopathology (Lubinski, 2000). In this article we: discuss a number of methodological errors commonly found in research on human individual differences; introduce a broad framework for interpreting findings from contemporary behavioral genetic studies; briefly outline the basic quantitative methods used in human behavioral genetic research; review the major criticisms of behavior genetic designs, with particular emphasis on the twin and adoption methods; describe the major or dominant theoretical scheme in each domain; and review behavioral genetic findings in all five domains. We conclude that there is now strong evidence that virtually all individual psychological differences, when reliably measured, are moderately to substantially heritable.