Sex differences in genetic and environmental influences on DSM-III-R attention-deficit/hyperactivity disorder

Approximately 5% of children are affected by attention-deficit/hyperactivity disorder (ADHD), and more boys are affected than girls. This study examined the magnitude of genetic and environmental influences on ADHD and several questions regarding sex differences in its prevalence and liability. The participants were 2,391 twin and sibling pairs from Australia, ages 3-18. ADHD symptoms in the general population were highly heritable (h2 = .85-.90), as were deviant ADHD scores in the selected population. The magnitude of familial influences was similar for boys and girls, although there were shared environmental influences on ADHD in girls but not boys and dominance genetic influences on ADHD in boys but not girls. Specific genetic and environmental influences were highly similar for boys and girls. Evidence supported the polygenic multiple threshold model rather than the constitutional variability model of sex differences in ADHD.     

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.     

Nonshared environmental influences and personality differences in adult twins

The twin design was used to examine the importance of different experiences of siblings within the family and to identify relations between twins' personality differences and their differential experiences. A sample of 161 monozygotic and 74 dizygotic twin individuals between the ages of 18 and 75 years retrospectively reported on their different experiences when growing up. The Sibling Inventory of Differential Experience (SIDE) was used for the first time with a sample of twin siblings. In addition, the twins provided self-report measures of affect and personality. In contrast to results from a sibling adoption design, this study of twins showed greater evidence for genetic variance in the SIDE scales. Nevertheless, the SIDE showed significant associations with differences in personality and affect for monozygotic twins, which reflect pure environment-behavior relations.     

Prosocial behavior from early to middle childhood: genetic and environmental influences on stability and change

Prosocial behavior is important for the functioning of society. This study investigates the extent to which environment shared by family members, nonshared environment, and genetics account for children's prosocial behavior. The prosocial behavior of twins (9,424 pairs) was rated by their parents at the ages of 2, 3, 4, and 7 and by their teachers at age 7. For parent ratings, shared environmental effects decreased from .47 on average at age 2 to .03 at age 7, and genetic effects increased from .32 on average to .61. The finding of weak shared environmental effects and large heritability at age 7 was largely confirmed through the use of teacher ratings. Using longitudinal genetic analyses, the authors conclude that genetic effects account for both change and continuity in prosocial behavior and nonshared environment contributes mainly to change.     

Genetic and environmental influences on antisocial behavior: a meta-analysis of twin and adoption studies

A meta-analysis of 51 twin and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on antisocial behavior. The best fitting model included moderate proportions of variance due to additive genetic influences (.32), nonadditive genetic influences (.09), shared environmental influences (.16), and nonshared environmental influences (.43). The magnitude of familial influences (i.e., both genetic and shared environmental influences) was lower in parent-offspring adoption studies than in both twin studies and sibling adoption studies. Operationalization, assessment method, zygosity determination method, and age were significant moderators of the magnitude of genetic and environmental influences on antisocial behavior, but there were no significant differences in the magnitude of genetic and environmental influences for males and females.     

Religiousness, antisocial behavior, and altruism: genetic and environmental mediation

Although religiousness is considered a protective factor against antisocial behaviors and a positive influence on prosocial behaviors, it remains unclear whether these associations are primarily genetically or environmentally mediated. In order to investigate this question, religiousness, antisocial behavior, and altruistic behavior were assessed by self-report in a sample of adult male twins (165 MZ and 100 DZ full pairs, mean age of 33 years). Religiousness, both retrospective and current, was shown to be modestly negatively correlated with antisocial behavior and modestly positively correlated with altruistic behavior. Joint biometric analyses of religiousness and antisocial behavior or altruistic behavior were completed. The relationship between religiousness and antisocial behavior was due to both genetic and shared environmental effects. Altruistic behavior also shared most all of its genetic influence, but only half of its shared environmental influence, with religiousness.     

Child and adolescent conduct disorder substantially shares genetic influences with three socioemotional dispositions

In a representative sample of twin children and adolescents, we tested the hypothesis that a substantial proportion of the genetic and environmental influences underlying conduct disorder (CD) are shared with three socioemotional dispositions: Prosociality, Negative Emotionality, and Daring. Caretaker ratings of each dispositional dimension were uniquely associated with a latent CD dimension that included both caretaker- and youth-reports of CD as indicators. Behavior genetic analyses indicated that moderate-to-high additive genetic and moderate nonshared environmental influences underlie all three dispositions and CD, with modest shared environmental influences on Prosociality. Forty percent of the additive genetic influences and all of the nonshared environmental influences on the latent CD dimension were shared in common with the three socioemotional dispositions. The finding that CD shares a substantial proportion of its genetic influences with three distinct socioemotional dispositions suggests new perspectives on the heterogeneous etiology of CD and new approaches to exploring its specific etiological mechanisms.     

Genetic and environmental bases of childhood antisocial behavior: a multi-informant twin study

Genetic and environmental influences on childhood antisocial and aggressive behavior (ASB) during childhood were examined in 9- to 10-year-old twins, using a multi-informant approach. The sample (605 families of twins or triplets) was socioeconomically and ethnically diverse, representative of the culturally diverse urban population in Southern California. Measures of ASB included symptom counts for conduct disorder, ratings of aggression, delinquency, and psychopathic traits obtained through child self-reports, teacher, and caregiver ratings. Multivariate analysis revealed a common ASB factor across informants that was strongly heritable (heritability was .96), highlighting the importance of a broad, general measure obtained from multiple sources as a plausible construct for future investigations of specific genetic mechanisms in ASB. The best fitting multivariate model required informant-specific genetic, environmental, and rater effects for variation in observed ASB measures. The results suggest that parents, children, and teachers have only a partly "shared view" and that the additional factors that influence the "rater-specific" view of the child's antisocial behavior vary for different informants. This is the first study to demonstrate strong heritable effects on ASB in ethnically and economically diverse samples.     

Modeling growth in boys' aggressive behavior across elementary school: links to later criminal involvement, conduct disorder, and antisocial personality disorder

The present study used general growth mixture modeling to identify pathways of antisocial behavior development within an epidemiological sample of urban, primarily African American boys. Teacher-rated aggression, measured longitudinally from 1st to 7th grade, was used to define growth trajectories. Three high-risk trajectories (chronic high, moderate, and increasing aggression) and one low-risk trajectory (stable low aggression) were found. Boys with chronic high and increasing trajectories were at increased risk for conduct disorder, juvenile and adult arrest, and antisocial personality disorder. Concentration problems were highest among boys with a chronic high trajectory and also differentiated boys with increasing aggression from boys with stable low aggression. Peer rejection was highest among boys with chronic high aggression. Interventions with boys with distinct patterns of aggression are discussed.     

Sex differences in gender-related childhood memories

Based on theories of gender development, especially the one proposed by Nancy Chodorow, it was predicted that boys' gender-related childhood memories will be different from girls' on five dimensions related to activity, emotionality, and sex appropriateness. Forty-five men and 45 women were asked to describe their earliest gender-related childhood memories. The memories were analyzed by two judges. The data document a significant sex difference in the activity and emotionality of the memories. Men's memories were more active and women's more emotional. The predictions that men's memories of sex-appropriate behavior will be more positive, will have fewer deviations from sex-appropriate behavior, and when such deviations occur, they will be associated with more negative emotions were not confirmed. It is suggested that childhood memories can be seen as reflecting actual differences between the sexes in childhood experiences, or as the result of a process of memory selection that reflects men's and women's different gender-related experiences as adults.The author would like to thank Beni Feinholtz and Naftali Menashe, both students at Tel Aviv University, for their help in the data collection.     

The predictive power of first-grade peer and teacher ratings of behavior: Sex differences in antisocial behavior and personality at adolescence

Peer and teacher assessments of aggression, social withdrawal, and likability using the Pupil Evaluation Inventory were recorded for 104 French Canadian girls and boys in grade 1. Self-reported delinquency and personality measures were administered to these children when they were in junior high school 7 years later. Linear regression analyses revealed significant predictive differences between the grade 1 assessment of girls and boys: For antisocial behavior, teacher and peer assessments of boys were equally good predictors, and the combination of the two assessments did not improve prediction; for girls, peer and teacher assessments taken separately were weak predictors, but, taken together, they were better predictors for girls than for boys; for personality, peers were better predictors than teachers both for girls and for boys. When categorical analyses were used to predict extreme antisocial behavior, peer and teacher assessments were equally good predictors for girls and boys. The use of peer and teacher ratings together, however, decreased the number of false positives. The implications of these findings for research and clinical work are discussed.     

Sex differences in dominance behavior

The effect of the status characteristic of sex on dominance behavior was investigated as a function of a challenger's sex and in relation to one's sex-role orientation. Dyads composed of a student and a confederate recorded individual preferences, then joint decisions, for the more attractive picture of 20 pairs of pictures. The number of challenges a student sustained each time a disagreement occurred regarding the more attractive picture of a pair was recorded. Males withstood significantly more challenges against their preferences than females did (p<.006). However, no differences were found as a function of the sex of one's partner; nor did the Attitudes toward Women Scale (AWS) prove to be a good predictor of dominance. Results were discussed in terms of predictions made by the theory of status characteristics.This report is based on a master's thesis written by the first author under the sponsorship of the second and submitted in partial fulfillment of the requirements for the MA degree at the Graduate School of the University of Alabama. Portions were presented as part of of the paper session Compliance-Conformity/Altruism-Helping Behavior at the annual meeting of the Southeastern Psychological Association, New Orleans, March 1976.The authors would like to express their appreciation those who served as confederates in this study: Jim Dodds, Rochelle Hanan, Eunice Fogarty, and Rex Hall.     

Sex differences in nonverbal behavior

A variety of nonverbal behaviors was coded from videotapes of 88 dyadic conversations. The 44 male and 44 female subjects were paired so that each participated in one conversation with a stranger of the same sex and one conversation with a stranger of the opposite sex. It was found that sex of subject, but not sex of partner, had a significant effect on many of the nonverbal behaviors displayed during the conversations. Subjects' scores on the behavioral measures were correlated with their scores on several personality measures and on a post-conversation questionnaire. Sex differences in these correlations were used to generate hypotheses linking specific behavioral differences between the sexes to more general differences between the masculine and feminine interpersonal styles.This study was supported in part by NSF grant GS-3033, awarded to Starkey Duncan, University of Chicago; by NSF grant GS-3127, awarded to Donald Fiske, University of Chicago; by a grant awarded to Starkey Duncan and Donald Fiske by the Social Science Divisional Research Committee of the University of Chicago; and by a University of Chicago Humanities Fellowship awarded to the author. The author is grateful to Starkey Duncan and Donald Fiske for the extensive assistance they provided with this study. The author also wishes to express her appreciation to Jeanine Carlson, George Niederehe, Bruno Repp, Thomas Shanks, and Cathy Stepanek, who assisted in coding the videotaped data and in the statistical analysis. This article is based on the author's doctoral dissertation (Beekman, 1973), which may be consulted for further details.Previous drafts of this article have been circulated under the author's former name, Susan J. Beekman.     

Sex differences in oppositional defiant disorder

The goal was to analyze the sex differences in symptoms, comorbidity and functional impairment in outpatient children with Oppositional Defiant Disorder (ODD). A sample of 343 children, aged 8 to 17 years and diagnosed with ODD, were assessed with a semi-structured diagnostic interview and dimensional measures of psychopathology and functional impairment. Boys with ODD more frequently displayed the symptoms "deliberately annoys" and "blames others", presented comorbid ADHD, and had greater functional impairment in school and community contexts; girls presented higher comorbidity with internalizing symptomatology (anxiety, depression and somatic complaints). Given that some clinical differences are apparent in ODD between boys and girls, it is necessary to consider the sex of the patient in order to identify and treat this disorder efficiently and effectively in boys and in girls.     

Genetic influences on the overlap between low IQ and antisocial behavior in young children

The well-documented relation between the phenotypes of low IQ and childhood antisocial behavior could be explained by either common genetic influences or environmental influences. These competing explanations were examined through use of the Environmental Risk Longitudinal Twin Study 1994-1995 cohort (Moffitt & the E-Risk Study Team, 2002) of 1,116 twin pairs and their families. Children's IQ was assessed via individual testing at age 5 years. Mothers and teachers reported on children's antisocial behavior at ages 5 and 7 years. Low IQ was related to antisocial behavior at age 5 years and predicted relatively higher antisocial behavior scores at age 7 years when antisocial behavior at age 5 years was controlled. This association was significantly stronger among boys than among girls. Genetic influences common to both phenotypes explained 100% of the low IQ-antisocial behavior relation in boys. Findings suggest that specific candidate genes and neurobiological processes should be tested in relation to both phenotypes.     

Genetic and environmental influences on adult attachment styles

The heritability of adult attachment styles as measured by the Relationship Scales Questionnaire (RSQ) was estimated on data from a volunteer general population sample of 220 adult twin pairs (116 monozygotic pairs. 104 dizygotic pairs). Additive genetic effects accounted for 37%, 43%, and 25% of the variance in the secure, fearful, and preoccupied adult attachment styles, respectively, but none of the variance in the dismissing style. Nonshared environmental influences accounted for the majority of the variance in all styles: 63% secure, 57% fearful, 75% preoccupied, and 71% dismissing. Shared environmental effects were negligible for all styles except dismissing (29%).     

Age differences in genetic and environmental influences on eating attitudes and behaviors in preadolescent and adolescent female twins

A sample of 680 11- and 602 17-year-old female twins was used to examine (a) age differences in genetic and environmental influences on disordered eating attitudes and behaviors and (b) associations between body mass index (BMI) and eating attitudes and behaviors. Univariate, biometrical model-fitting analyses indicated that 11-year-old twins exhibited less genetic and greater shared environmental influence on eating attitudes and behaviors than 17-year-old twins. Bivariate model-fitting analyses indicated that the relationship between BMI and eating attitudes was mediated primarily by common shared environmental influences in 11-year-old twins and common genetic influences in 17-year-old twins. Nonetheless, the majority of genetic influences on eating attitudes and behaviors in older twins were due to genetic effects that are independent of those operating in BMI.     

The nature of environmental influences on weight and obesity: a behavior genetic analysis.

The nature of environmental influences on individual differences in weight and obesity is presently unclear. To resolve this issue, behavior genetic studies are reviewed for their relevance to environmental influences on weight and obesity. Results are consistent in suggesting that environmental experiences are important for weight and obesity, although they account for much less variation than do the effects of genes. Furthermore, only environmental experiences that are not shared among family members appear to be important. In contrast, experiences that are shared among family members appear largely irrelevant in determining individual differences in weight and obesity. These conclusions are consistent with a growing body of evidence on the relative unimportance of such shared experiences for many psychological characteristics.     

Substance use and violent behavior in women with antisocial personality disorder

The purpose of this study was to examine the relationship between substance abuse and dependence and violent behavior in a sample of incarcerated women with antisocial personality disorder (ASPD). Among male populations, substance dependence is associated with aggression and criminal behavior. Individuals with ASPD have more severe substance dependence, including higher symptom counts, earlier age of onset, and more frequent co-morbidity. Incarcerated women have a high prevalence of ASPD and substance dependence, but there has been little detailed work regarding addiction severity. Similarly, work on association of substance abuse and dependence with specific violent behaviors has been limited. This study examined a group of 41 mid-sentence female felons with a diagnosis of ASPD to determine associations with substance abuse and dependence. Data were gathered through administration of the Semi-Structured Assessment of the Genetics of Alcoholism II (SSAGA II). Substance dependence was highly prevalent (i.e., alcohol dependence, 56.1%; opiate dependence, 48.8%; cocaine dependence, 61.0%). While specific diagnoses were not associated with violent behavior and offending, symptom severity (i.e., age of onset, symptom count, co-morbidity) was associated with violent behavior in women dependent on opiates, alcohol, and cocaine. Arrest for an assault 1 was associated with alcohol dependence and opiate dependence. These data suggest that measurement of symptom severity and co-morbidity is important in assessing violent behavior in incarcerated women with ASPD. These findings are potentially important in examining non-incarcerated, substance-dependent women.