Genetic and environmental sources of continuity and change in teacher‐rated aggression during early adolescence

Genetic and environmental sources of continuity and change in aggression were studied in a sample of 1,041 twin pairs (364 monozygotic; 348 same‐sex dizygotic; and 329 opposite‐sex dizygotic) as part of an ongoing, population‐based Finnish twin‐family study. At ages 12 and 14, the twins' aggression was assessed by their classroom teachers, using a rating form of the Multidimensional Peer Nomination Inventory. Genetic and environmental sources of continuity and change were studied by fitting a longitudinal bivariate Cholesky decomposition model. Longitudinal model‐fitting results indicated that both genetic and environmental factors influenced continuity in aggression during this 2‐year period, but the age‐to‐age correlation of these factors differed by sex. Continuity in boys' aggression was mediated by genes and common environmental factors; in girls, in contrast, continuity was due primarily to common environmental, and to a lesser degree, unique environmental factors. Genes and unique environments contributed to change in aggression in both sexes. Aggr. Behav. 31:1–13, 2006. © 2006 Wiley‐Liss, Inc.     

Genetic and environmental influences on interpersonal cognitions and associations with depressive symptoms in 8-year-old twins

Less is known about depression in children than in adults. This study integrates fields by combining cognitive and interpersonal research investigating childhood depression symptoms through the use of a genetic framework. Three research questions are addressed. First, what are the associations among interpersonal cognitions, anxiety, and depression? Second, what are the relative magnitudes of genetic and environmental influences on interpersonal cognitions? Third, to what extent do genetic and environmental influences explain associations between interpersonal cognitions and depression? Three hundred pairs of 8-year-old twins reported on symptoms of depression and anxiety by completing the Children's Depression Inventory and the Screen for Childhood Anxiety-Related Emotional Disorders. The authors examined interpersonal cognitions with the Children's Expectation of Social Behaviors and the Perceptions of Peers and Self Questionnaires. Interpersonal cognitions were more strongly correlated with depression (mean r = .35) than with anxiety (mean r = .13). Genetic influence on interpersonal cognitions was small (M = 3%), and associations between interpersonal cognitions and depression were mainly explained by environmental influences. These latter findings may result from interpersonal cognitions in young children, reflecting life experiences as opposed to trait-like cognitive biases.     

Genetic and environmental stability differs in reactive and proactive aggression

The aim of this study was to examine stability and change in genetic and environmental influences on reactive (impulsive and affective) and proactive (planned and instrumental) aggression from childhood to early adolescence. The sample was drawn from an ongoing longitudinal twin study of risk factors for antisocial behavior at the University of Southern California (USC). The twins were measured on two occasions: ages 9–10 years (N=1,241) and 11–14 years (N=874). Reactive and proactive aggressive behaviors were rated by parents. The stability in reactive aggression was due to genetic and nonshared environmental influences, whereas the continuity in proactive aggression was primarily genetically mediated. Change in both reactive and proactive aggression between the two occasions was mainly explained by nonshared environmental influences, although some evidence for new genetic variance at the second occasion was found for both forms of aggression. These results suggest that proactive and reactive aggression differ in their genetic and environmental stability, and provide further evidence for some distinction between reactive and proactive forms of aggression. Aggr. Behav. 35:437–452, 2009. © 2009 Wiley‐Liss, Inc.     

Age differences in the prevalence of physical aggression among 5-11-year-old Canadian boys and girls

It has been proven extremely difficult in the past to estimate the prevalence of physical aggression in children for two main reasons: (a) a heterogeneous sampling of behaviors (i.e., mix between physically aggressive and non-physically aggressive antisocial behaviors), and (b) a lack of a "gold standard" to identify children who exhibit physically aggressive behaviors on a frequent basis. The goal of this study was to test for age differences in the prevalence of physical aggression in the Canadian population of school-aged boys and girls, using cross-sectional data from the National Longitudinal Survey of Children and Youth (NLSCY). The first wave of the NLSCY included a representative sample of 12,292 Canadian children aged 5-11 years. We used latent class analysis to identify children whose propensity to exhibit physically aggressive behaviors was much higher than that of other children of the same age and sex in the population. The prevalence of physical aggression was estimated at 3.7% in 5-11-year-old boys and ranged from .5% to 2.3% in 11 and 5-year-old girls, respectively. Hence, the results show a decreasing trend in the prevalence of physical aggression with age for girls, but not for boys. These findings suggest the importance of considering the developmental pathways of physical aggression for boys and girls separately.     

Effects of early exposure to intermale aggression on the aggressiveness of adult male mice varying in their genetic disposition for aggressive behavior

This study examined whether adult male aggression is influenced by either visual or olfactory exposure in early postnatal life to brief episodes of aggression. Another focus of interest was the interplay between a genetic disposition for aggressive behavior and early exposure experiences. The subjects used in the study were male mice of the 49th generation of selection for high (Turku Aggressive, TA) and low (Turku Non-Aggressive, TNA) levels of aggressiveness. Moderately aggressive males of the parental strain (Normal, N) were also used. Subjects of each strain were exposed from 21 to 32 days of age to fighting males either behind a wire mesh or glass screen. Control subjects were isolated during the entire experimental period. At 90–100 days of age, each subjects was tested three times for its aggressiveness. Exposure to fighting males behind a wire mesh screen enhanced later aggressiveness of juvenile male mice. Juveniles exposed solely to visual cues were comparable to isolates, both groups showing less adult aggression. Early experience and the genetic disposition for aggression were correlated; TA males showing the greatest increase in aggressive behavior. The role of early olfactory learning is discussed. © 1993 Wiley-Liss, Inc.     

Sex differences in genetic and environmental effects on aggression

The aim of the present study was to investigate the genetic and environmental factors influencing teacher and parental rated aggression in boys and girls, asking whether the magnitude of these effects is similar across rater and sex. The study is part of an ongoing nationwide twin‐family study of behavioral development and health habits carried out in Finland. The sample consisted of 1651 twin pairs (264 monozygotic male, 300 monozygotic female, 292 dizygotic male, 278 dizygotic female, and 517 dizygotic opposite‐sex twin pairs), representing subsets of five 11‐ to 12‐year‐old twin cohorts (b. 1983–1987). The data were collected using the teacher and parental rating forms of the Multidimensional Peer Nomination Inventory. Structural equation models of sex‐limitation assessed sex differences in genetic and environmental influences on aggression. The results suggested significant genetic, common environmental, and specific environmental effects on aggression in both boys and girls, but the best fitting model differed depending on the informant. For both ratings, boys showed lower levels of heritability and higher levels of common environment than girls. In addition, the teacher rating data also suggested the presence of either sex‐specific common environmental effects or sex‐specific genetic effects. Support is provided also for sibling contrast effects, either at the behavioral level or as a rater bias. Aggr. Behav. 29:55–68, 2003. © 2003 Wiley‐Liss, Inc.     

Social‐cognitive mediators of the relation of environmental and emotion regulation factors to children's aggression

Tested a theoretical model in which social cognitions about aggression partially mediated the relation of environmental and emotion regulation factors to children's aggressive behavior. An ethnically diverse sample of 778 children (57% girls) in grades 4–6 from both urban and suburban schools participated. Measures included exposure to aggression (seeing/hearing about aggression, victimization), emotion regulation (impulsivity, anger control), social cognitions about aggression (self‐evaluation, self‐efficacy, retaliation approval, aggressive fantasizing, caring about consequences), and aggressive behavior. Results supported the hypothesis that social cognitions mediate the relations of exposure to aggression and anger control to aggressive behavior. Also, social cognitions about direct and indirect aggression differentially predicted the respective behaviors with which they are associated. That is, social cognitions about direct aggression were mediators of direct aggressive behavior, whereas social cognitions about indirect aggression were mediators of indirect aggressive behavior. Finally, gender moderated the relations among the variables such that for girls, retaliation approval beliefs were a strong mediator, whereas for boys, self‐evaluation was more important. Aggr. Behav. 30:389–408, 2004. © 2004 Wiley‐Liss, Inc.     

Genetic and environmental influences on individual differences in printed word recognition

The genetic and environmental etiologies of individual differences in printed word recognition and related skills were explored in 440 identical and fraternal twin pairs between 8 and 18 years of age. A theoretically driven measurement model identified five latent variables: IQ, phoneme awareness, word recognition, phonological decoding, and orthographic coding. Cholesky decomposition models on these five latent constructs revealed the existence of both common and independent genetic effects, as well as non-shared environmental influences. There was evidence for moderate genetic influences common between IQ, phoneme awareness, and word-reading skills, and for stronger IQ-independent genetic influences that were common between phoneme awareness and word-reading skills, particularly phonological decoding. Phonological and orthographic coding skills in word recognition had both significant common and significant independent genetic influences, with implications for "dual-route" and "connectionist" reading models, subtypes of reading disabilities, and the remediation of reading disabilities.     

Genetic and environmental influences on the Verbal-Perceptual-Image Rotation (VPR) model of the structure of mental abilities in the Minnesota study of twins reared apart

In previous papers [Johnson, W., & Bouchard Jr., T. J. (2005a). Constructive Replication of the Visual-Perceptual-Image Rotation (VPR) Model in Thurstone's (1941) Battery of 60 Tests of Mental Ability. Intelligence, 33, 417–430.] [Johnson, W., & Bouchard Jr., T. J. (2005b). The Structure of Human Intelligence: It's Verbal, perceptual, and image rotation (VPR), not Fluid and Crystallized. Intelligence, 33, 393–416.] we have proposed the Verbal, perceptual, and image rotation (VPR) model of the structure of mental abilities. The VPR model is hierarchical, with a g factor that contributes strongly to broad verbal, perceptual, and image rotation abilities, which in turn contribute to 8 more specialized abilities. The verbal and perceptual abilities, though separable, are highly correlated, as are the perceptual and mental rotation abilities. The verbal and mental rotation abilities are much less correlated. In this study we used the twin sample in the Minnesota Study of Twins Reared Apart to estimate the genetic and environmental influences and the correlations among them at each order of the VPR model. Genetic influences accounted for 67–79% of the variance throughout the model, with the exception of the second-stratum Content Memory factor, which showed 33% genetic influence. These influences could not be attributed to assessed similarity of rearing environment. Genetic correlations closely mirrored the phenotypic correlations. Together, these findings substantiate the theory that the entire structure of mental abilities is strongly influenced by genes.     

Exposure to maternal vs. paternal partner violence,PTSD, and aggression in adolescent girls and boys

Adolescents who witness interparental violence (IPV) are at increased risk for perpetrating aggressive acts. They are also at risk for post‐traumatic stress disorder (PTSD). In this study, we examined the relation between exposure to maternal vs. paternal physical IPV and adolescent girls' and boys' aggressive behavior toward mothers, fathers, friends, and romantic partners. We also assessed the influence of PTSD (as assessed by the Diagnostic Interview for Children and Adolescents‐IV (DICA‐IV)) on the relation between exposure to IPV and aggressive behavior. Participants were 63 girls and 49 boys, ages 13–18, consecutively admitted to a youth correctional facility or assessment facility designated to serve aggressive and delinquent youth. Structural equation modeling was used to estimate unique relations between exposure to maternal vs. paternal IPV and youth aggression in relationships. Girls who observed their mothers' aggressive behavior toward partners were significantly more aggressive toward friends. Similarly, boys who witnessed their fathers' aggression were significantly more aggressive toward friends. Adolescent girls and boys who observed aggression by mothers toward partners reported significantly higher levels of aggression toward their romantic partners. Approximately one third of our sample met PTSD criteria; the relation between exposure to parental IPV and aggression was stronger for individuals who met criteria for PTSD. The implications of understanding the relations between parents' and their daughters' and sons' use of aggression are discussed within the context of providing support for families in breaking intergenerational patterns of violence and aggression. Aggr. Behav. 32:385–395, 2006. © 2006 Wiley‐Liss, Inc.     

Genetic and environmental influences on executive functions and intelligence in middle childhood

Executive functions (EFs) and intelligence (IQ) are phenotypically correlated. In twin studies, latent variables for EFs and IQ display moderate to high heritability estimates; however, they show variable genetic correlations in twin studies spanning childhood to middle age. We analyzed data from over 11,000 children (9- to 10-year-olds, including 749 twin pairs) in the Adolescent Brain Cognitive Development (ABCD) Study to examine the phenotypic and genetic relations between EFs and IQ in childhood. We identified two EF factors—Common EF and Updating-Specific—which were both related to IQ (rs = 0.64–0.81). Common EF and IQ were heritable (53%–67%), and their genetic correlation (rG = 0.86) was not significantly different than 1. These results suggest that EFs and IQ are phenotypically but not genetically separable in middle childhood, meaning that this phenotypic separability may be influenced by environmental factors.     

Study on the relations between temperament,aggression, and anger in children

The present work analyzes the relationships between the dimensions of temperament and the exteriorized emotions of aggression and anger. Temperament was assessed by mothers using the Dimensions of Temperament Survey‐Revised, while aggression and anger were self‐reported by the children using the Scale of physical and Verbal Aggression and the State–Trait Anger Expression Inventory for Children. The sample studied was made up of 293 children (49.83% boys; 50.17% girls) with a mean age of 11.13 years. The results showed that temperamental difficulties give rise to exteriorized emotions, especially anger. Predictive values of temperament on aggression and anger ranged from 1% to 7% of explained variance. Aggr. Behav. 32:207–215, 2006. © 2006 Wiley‐Liss, Inc.     

Genetic and environmental influences on the association between performance‐based self‐esteem and exhaustion: A study of the self‐worth notion of burnout

In the self‐worth model, burnout is considered to be a syndrome of performance‐based self‐esteem (PBSE) and experiences of exhaustion. Studies have shown that PBSE and burnout indices such as Pines’ Burnout Measure (BM) are associated. Whether these variables have overlapping etiologies has however not been studied before. Genetic and environmental components of covariation between PBSE and exhaustion measured with Pines’ BM were examined in a bivariate Cholesky model using data from 14,875 monozygotic and dizygotic Swedish twins. Fifty‐two per cent of the phenotypic correlation (r = 0.41) between PBSE and Pines’ BM was explained by genetics and 48% by environmental factors. The findings of the present study strengthen the assumption that PBSE should be considered in the burnout process as proposed by the self‐worth conception of burnout. The present results extend our understanding of the link between this contingent self‐esteem construct and exhaustion and provide additional information about the underlying mechanisms in terms of genetics and environment. This finding corroborates the assumed syndrome view on burnout, while it also suggests an altered view of how the syndrome emerges and how it can be alleviated.     

Differential correlates of reactive and proactive aggression in Asian adolescents: relations to narcissism, anxiety, schizotypal traits, and peer relations

This study investigated relationship between reactive and proactive aggression, and narcissism, anxiety, schizotypal traits, and interpersonal relations in a sample of 698 Asian adolescents from Grades 7 to 9. Proactive aggression was found to be significantly associated with narcissism, whereas reactive aggression was significantly associated with anxiety, schizotypal traits, and poor interpersonal relations. Study findings provide support from a cross-cultural standpoint for differential correlates of reactive and proactive aggression and represent an initial attempt to illustrate the generalizability of existing findings on the distinction between the two subtypes in an Asian context. Implications for theory building of the reactive-proactive aggression typology are discussed.     

Influence of executive functioning difficulties on verbal aggression in adolescents: Moderating effects of winning and losing and increasing and decreasing levels of provocation

We examined the extent to which executive functioning difficulties were related to verbal aggression under conditions of gradually increasing or decreasing provocation over both winning and losing trials. Sixty adolescent boys and girls completed a modified Taylor aggression paradigm in which verbally offensive remarks were sent and received. Results showed (a) that during increasing levels of provocation, verbal aggression increased on both winning and losing trials, (b) that verbal aggression decreased during decreasing levels of provocation but only on losing trials, and (c) that difficulties on two measures of executive functioning were related to verbal aggression, but only in the context of increasing verbal provocation. Individuals with executive functioning difficulties responded with more verbal aggression than did individuals with less severe executive functioning difficulties. Results have implications for the manner in which provocation is studied and for understanding the conditions in which executive functioning difficulties contribute to verbal aggression. Aggr. Behav. 29:475–488, 2003. © 2003 Wiley‐Liss, Inc.     

Covariation of self‐ and other‐directed aggression among inpatient youth: continuity in the transition to treatment and shared risk factors

Although other‐ and self‐directed aggression covary in very high‐risk youth, these forms of aggression infrequently are studied simultaneously. Understanding better their covariation is an important task for improving services to high‐risk youth. In this study, data from the clinical records of 476 youth admitted to secure inpatient treatment were analyzed to examine relations among self‐ and other‐directed aggression exhibit before and during inpatient treatment. Analyses tested the hypotheses that self‐ and other‐directed aggression would tend to covary and display continuity from pre‐treatment to in‐treatment. Also tested were the hypotheses that youth with histories of co‐occurring self‐ and other‐directed aggression would show the highest levels of aggression during treatment and the greatest degree of personal and contextual risk on entering treatment. These hypotheses were largely supported. Exploratory analyses revealed interesting discontinuities in aggression (aggression emitted only before or during treatment) with critical implications for research and practice with youth receiving clinical care, especially those in institutional placements. Aggr. Behav. 36:205–217, 2010. © 2010 Wiley‐Liss, Inc.     

Gender attribution and gender agreement in 4- to 10-year-old French children

Grammatical gender is generally considered an early and error-free acquisition in French children. This article first examines how children cope with the gender attribution problem, i.e., how they determine the gender of individual nouns. We consider the plausibility and requirements of an account in which tacit phonological assignment rules are put to use to solve attribution problems and contrast it with a simple “masculine as default” strategy. Elicited production data from three experiments, involving 312 4–10-year-old French children and 40 adult controls, were found compatible with this latter scenario and to provide only scant support for the former one. Second, we argue that previous studies have overestimated French children's gender agreement abilities, and that French children's ability to make the article and the adjective agree can be assumed from age 7 onwards, but not before.     

Genetic and Environmental Influences on Personal and Rhythmic‐Motor‐Activity Tempo in Children: A Twin Study

In this study, we investigated the degree to which genetics and environmental factors influence the tempo and tempo stability of rhythmic motor activity in young children, using a twin study design. A total of 116 twin children, aged 4 years, were asked to strike two small clash cymbals together in a cyclical manner, in three phases. In the first phase, children were asked to maintain a comfortable personal tempo of rhythmic motor activity (spontaneous motor phase). In contrast, in the other phases, children were required to synchronize rhythmic motor activity in response to the timing of a stimulus tone, or a memorized tempo. Large additive genetic, although negligible shared environmental influences, were observed in the spontaneous motor phase. However, environmental factors were estimated in the other two phases, while the additive genetic factor was nearly zero. These results indicate that the extent of genetic and environmental influences on individual differences in rhythmic motor activity can be modulated under different situations.     

The Boston Naming Test: Norm data and cue utilization in a sample of normal 6- and 7-year-old children

The object-naming abilities of 83 normal children were examined using the Boston Naming Test developed by E. Kaplan, H. Goodglass, and S. Weintraub (1976, The Boston Naming Test (experimental edition), unpublished test, Veterans Hospital, Boston, Massachusetts). There is currently a lack of available norms for this instrument, especially for populations of younger children. Cue utilization in this sample is explored and attention is focused upon possible gender differences in naming performance and cue strategies. Seven summary scores derived from the test are presented in this report. Results indicate that the Boston Naming Test can discriminate within a normal population sample of young children and provides a relatively normal distribution for six of seven derived scores. Boys were found to have a significantly greater number of items correctly named but no gender differences in cue utilization were evident. A major proportion of the children in this sample of 6- and 7-year-olds used phonological cues almost exclusively, rather than semantic cues also provided. Cue use was not related to age or spontaneously given responses, and none of the children were found to be highly proficient at using both types of cues.