How Heritable are Parental Sensitivity and Limit-Setting? A Longitudinal Child-Based Twin Study on Observed Parenting

We examined the relative contribution of genetic, shared environmental and non-shared environmental factors to the covariance between parental sensitivity and limit-setting observed twice in a longitudinal study using a child-based twin design. Parental sensitivity and parental limit-setting were observed in 236 parents with each of their same-sex toddler twin children (M_age = 3.8 years; 58% monozygotic). Bivariate behavioral genetic models indicated substantial effects of similar shared environmental factors on parental sensitivity and limit-setting and on the overlap within sensitivity and limit-setting across 1 year. Moderate child-driven genetic effects were found for parental limit-setting in year 1 and across 1 year. Genetic child factors contributing to explaining the variance in limit-setting over time were the same, whereas shared environmental factors showed some overlap.     

Genetic and Environmental Influences on Perceptions of Self-Worth and Competence in Adolescence: A Study of Twins, Full Siblings, and Step-Siblings

Although it is generally assumed that the origins of adolescents' perceptions of self-competence lie in shared family environmental influences, the contributions of nonshared environmental or genetic influences have not been explored. We investigated sibling resemblance for perceived competence and self-worth in 720 adolescent pairs aged 10 to 18 years, using a twin, full sibling, and step-sibling design. Our goals were to assess the magnitude of shared and nonshared environmental influences and to disentangle resemblance due to shared genetic heritage from that due to shared environmental experiences. Shared environment was not significant for any of the scales. 4 of the subscales showed significant genetic influence: scholastic, social, physical, and athletic competence. We also explored possible sources of genetic influences on perceived competence. Bivariate models revealed common genetic variance between scholastic competence and vocabulary and social competence and sociability. These measures, however, did not account for all of the genetic variance in perceived social and scholastic competence.     

Environmental and Genetic Variance in Children's Observed and Reported Maladaptive Behavior

The genetic and environmental contributions to children's maladaptive behavior are assessed in a sample of 154 twin pairs (77 MZ twin pairs and 77 DZ twin pairs), who range in age from 6 to 11 years. To bridge the strengths of behavioral genetic methods and environmental assessment techniques, we use a multimethod, multimeasure approach to data collection, and analyze the data using behavioral genetic modeling techniques. Results indicate that genetic variation accounts for a majority of the variance in parent-reported child maladaptive behavior (average = 62%). One parent-report measure also suggests a smaller, significant contribution of shared environmental variance. In contrast to the parental ratings, the observational coding and global impressions of parent-twin interactive behavior suggest that shared environment is the primary source of variance accounting for parent and child maladaptive behavior. This is due, in part, to the direct influence one's interactive partner has on the expression of maladaptive behavior in an interactive setting. When controlling for the co-participant's behavior, genetic variation increases and shared environmental variation decreases.     

Predicting individual differences in reading comprehension: a twin study

We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap among phonological decoding, word recognition, listening comprehension, vocabulary, and reading comprehension was primarily due to genetic influences. Shared environmental influences accounted for associations among word recognition, listening comprehension, vocabulary, and reading comprehension. Independent of phonological decoding and word recognition, there was a separate genetic link between listening comprehension, vocabulary, and reading comprehension and a specific shared environmental link between vocabulary and reading comprehension. There were no residual genetic or environmental influences on reading comprehension. The findings provide evidence for a genetic basis to the “Simple View” of reading.     

A Good Story: Children With Imaginary Companions Create Richer Narratives

In line with theories that children's pretend play reflects and extends their narrative skills, children with imaginary companions were predicted to have better narrative skills than children without imaginary companions. Forty-eight 5½-year-old children and their mothers participated in interviews about children's imaginary companions. Children also completed language and narrative assessments. Twenty-three of the children (48%) were deemed to have engaged in imaginary companion play. Children with and without imaginary companions were similar in their vocabulary skills, but children with imaginary companions told richer narratives about a storybook and a personal experience compared to children without imaginary companions. This finding supports theories of a connection between pretend play and storytelling by the end of early childhood.     

Genetic Influences on Activity Level in Early Childhood: Do Situations Matter?

Although genetic influences on individual differences in activity level (AL) are well documented, few studies have considered the etiology of AL from a contextual perspective. In the present study, cross-situational and context-specific genetic effects on individual differences in AL at age 2 were examined. The AL of 312 twin pairs (144 monozygotic and 168 dzygotic) was mechanically assessed with actigraphs in the home and in laboratory test and play situations. AL displayed significant genetic variance in all 3 situations. Moreover, actigraph scores significantly correlated across situations. Multivariate genetic model-fitting analyses found that the observed cross-situational continuity in AL was due entirely to genetic factors. Situational differences in AL arise from genetic, shared environmental, and nonshared environmental influences.     

Genetic and environmental influences on sex-typed behavior during the preschool years

The genetic and environmental etiologies of sex-typed behavior were examined during the preschool years in a sample of 3,990 three- to four-year-old twin and non-twin sibling pairs. Results showed moderate genetic and significant shared environmental influence for boys and substantial genetic and moderate shared environmental influence for girls. For both boys and girls, twin-specific shared environmental effects contributed to twins' similarity in gender role behavior and accounted for approximately 22% of the shared environmental variance. These findings extend previous research conducted with older samples by showing not only important genetic contributions to gender role behavior but also an important role for shared environment. The inclusion of non-twin siblings showed that some of the shared environmental influence is specific to twins.     

A taxonomic view of pretend play activity among 4- and 5-year-old children

Based on findings from a 6-month study that explored the nature of literate behavior in the pretend play episodes of eight preschoolers, a taxonomy of their pretend play activity is described and analyzed. Relationships between the different kinds of pretend play activity as demonstrated by these youngsters are examined in light of the taxonomy and other research. Implications of certain kinds of pretend play activity for emergent literacy development are also briefly discussed.     

Aggression in Pretend Play and Aggressive Behavior in the Classroom

Research Findings: Pretend play is an essential part of child development and adjustment. However, parents, teachers, and researchers debate the function of aggression in pretend play. Different models of aggression predict that the expression of aggression in play could either increase or decrease actual aggressive behavior. The current study examined pretend play and classroom behavior in preschoolers. Children (N = 59) were administered a measure of pretend play, and teacher ratings of classroom behavior were obtained. Pretend play skills were positively associated with prosocial behavior in the classroom and negatively associated with physical aggression in the classroom. In particular, expression of oral aggression in play related to less physical aggression and more prosocial behavior in the classroom. Practice or Policy: These findings suggest that pretend play should be encouraged, as these skills relate to positive behaviors in the classroom. In addition, it was found that aggression in pretend play was not an indicator of actual aggressive behavior, as it related to positive behaviors in the classroom. Implications for parents and teachers are discussed.     

Why are hyperactivity and academic achievement related?

Although a negative association between hyperactivity and academic achievement is well documented, little is known about the genetic and/or environmental mechanisms responsible for the association. The present study explored links between parent and teacher ratings of hyperactive behavior problems and teacher-assessed achievement in a sample of 1,876 twin pairs (mean age 7.04 years). The results did not differ across rater, nor were there significant differences between males or females or for twins in the same or different classrooms. Hyperactivity was significantly correlated with achievement. Multivariate model-fitting analyses revealed significant genetic and nonshared environmental covariance between the two phenotypes. In addition, bivariate heritabilities were substantial, indicating that the phenotypic correlations between hyperactivity and achievement were largely mediated by genetic influences.     

Genetic and environmental etiologies of reading disability: A twin study

Previous twin studies of reading disability employed a comparison of concordance rates in identical and fraternal twin pairs as a test for genetic etiology. Recently, a statistically more powerful multiple regression analysis of twin data has been formulated to assess the importance of genetic factors in the development of reading difficulties. Application of this analysis to twin data from the Colorado Reading Project yields definitive evidence for a genetic etiology. Results from this study suggest that approximately 40 percent of the deficit observed in the disabled readers is due to genetic factors, 35 percent is due to environmental influences shared by members of twin pairs, and about 25 percent is the result of environmental factors unique to the individual and/or error variance. This work was supported in part by a program project grant from the NICHD (HD-11681).     

儿童假扮游戏中的认知技能发展

假扮游戏的出现、发展到成熟伴随儿童的认知发展．儿童需要具备必要的认知技能才能参与假扮游戏,与假扮游戏有关的认知技能主要包括:社会参照、解读意图、分离、符号化假扮、角色扮演等．假扮游戏与儿童认知发展是一个交互作用的过程,作用的起点是假扮行为的出现．     

Links Between Preschool Children’s Social Skills and Observed Pretend Play in Outdoor Childcare Environments

As one of the most advanced play forms in childhood, pretend play often demonstrates positive associations with children’s development. However, results from research that examines the association between social skills and pretend play are mixed, especially when the complexity of pretend play is taken into account. Moreover, few studies on pretend play are conducted in outdoor environments; a setting which affords many opportunities for engagement in pretend play and unstructured social interactions. By observing children’s outdoor pretend play, the primary purpose of this study was to investigate the relationships between different types of pretend play and children’s social skills. Twenty-eight children from high quality childcare centers in a southeast suburban area were observed during outdoor free play time. Using a reliable time sampling protocol, each child’s play was observed and recorded for a total of 45 min to an hour over a 2-week time period. Lead teachers rated children’s social skills in the areas of cooperation, self-control, and assertiveness. Results showed high amounts of pretend play behavior overall, and differential relationships between the type of pretend play children engaged in and children’s social skills. Surprisingly, these relationships were not associated with gender. Findings are discussed in light of the value of pretend play to promote social skill development and the potential for outdoor contexts specifically to encourage these play behaviors.     

The Relation Between Toy Gun Play and Children's Aggressive Behavior

To assess the relation between toy gun play and aggression, thirty-six 3- to 5-year-olds were observed in free play in their daycare center and coded for amount of real aggression, pretend aggression, rough-and-tumble play (R & T), and nonaggressive pretend play. Based on a questionnaire completed by the parents, the children were also coded for the amount they played with toy guns in the home, the rated aggressive level of their preferred television programs, the rated aggressive level of their most preferred toys, and amount of parents' physical punishment of the children. Of all children, 56% played with toy guns in the home, most of whom were boys. Multiple regression analyses indicated that amount of parents' punishment strongly predicted real aggression in both boys and girls, and amount of toy gun play strongly predicted real aggression in boys. However, when it came to pretend aggression, aggressive level of children's preferred toys was the strongest predictor, while toy gun play negatively predicted pretend aggression. Toy gun play did not predict nonaggressive pretend play, but parents' punishment negatively predicted nonaggressive pretend play. These results indicate that toy gun play and parental punishment are positively associated with a higher level of real aggression but not pretend aggression. This pattern is discussed in terms of a cuing effect theory versus a cathartic effect theory. It also argues for distinguishing between real and pretend aggression and other forms of play in future studies.     

Adverse childhood experiences,health perception,and the role of shared familial factors in adult twins

To examine the relationship between adverse childhood experiences (ACE) and health perception in adulthood, and to explore the contribution of shared familial factors to these associations. Data were collected from 180 female twins (90 pairs) from the community-based University of Washington Twin Registry. Participants completed questionnaires including the modified ACE Questionnaire, Traumatic Life Events Questionnaire, McGill Pain Questionnaire-Short Form, and the SF-36. Mixed effects linear regression modeling investigated the effects of ACE on indices of health perception controlling for correlated twin data. Additional models examined the associations while controlling for the experience of physical and/or sexual abuse in childhood; within-twin pair models that inherently adjust for familial factors explored shared familial influences. After controlling for relevant demographic variables, more ACE was associated with worse perceptions of general health (p = .01) and vitality (p = .05) on the SF-36. After controlling for childhood physical and/or sexual abuse, the relationship between ACE and general health remained significant (p = .01) while vitality was no longer significant. None of the associations remained significant after accounting for the influence of familial factors. These results support previous findings on the negative link between ACE and perceived health in adulthood. The detrimental effects of ACE on vitality may be accounted for by the experience of childhood physical and/or sexual abuse. Shared familial factors might play a partial role in the relationship between ACE and health perception. Future research should further investigate the genetic and environmental mechanisms that may explain this relationship.     

A Twin Study of Attachment in Preschool Children

The degree to which individual differences in child-parent attachment were mediated by genetic, shared environmental, and nonshared environmental influences was investigated. One hundred and ten preschool-aged twin pairs (N = 220) were assessed in the Strange Situation and coded using conventional four-way classifications and a continuous measure of attachment security. The degree of sibling similarity in attachment was substantial, with an overall concordance rate of 67% at the secure/insecure level. The degree of concordance was equally high in monozygotic and dizygotic twin pairs, 70% and 64%, respectively, suggesting little genetic influence but a moderate degree of discordance. Twin similarity on the continuous measure of attachment security was r(57) = .48 and r(53) = .38 for monozygotic and dizygotic twin pairs, respectively, also consistent with a modest role for genetic influence but a significant effect for shared and nonshared environment. The implications for genetic influences on the environment and for understanding nonshared and shared environmental influences are discussed.     

The Relation Between Toy Gun Play and Children's Aggressive Behavior

To assess the relation between toy gun play and aggression, thirty-six 3- to 5-year-olds were observed in free play in their daycare center and coded for amount of real aggression, pretend aggression, rough-and-tumble play (R & T), and nonaggressive pretend play. Based on a questionnaire completed by the parents, the children were also coded for the amount they played with toy guns in the home, the rated aggressive level of their preferred television programs, the rated aggressive level of their most preferred toys, and amount of parents' physical punishment of the children. Of all children, 56% played with toy guns in the home, most of whom were boys. Multiple regression analyses indicated that amount of parents' punishment strongly predicted real aggression in both boys and girls, and amount of toy gun play strongly predicted real aggression in boys. However, when it came to pretend aggression, aggressive level of children's preferred toys was the strongest predictor, while toy gun play negatively predicted pretend aggression. Toy gun play did not predict nonaggressive pretend play, but parents' punishment negatively predicted nonaggressive pretend play. These results indicate that toy gun play and parental punishment are positively associated with a higher level of real aggression but not pretend aggression. This pattern is discussed in terms of a cuing effect theory versus a cathartic effect theory. It also argues for distinguishing between real and pretend aggression and other forms of play in future studies.     

Evidence for Common Etiological Influences on Early Literacy Skills in Kindergarten

Understanding how the etiology of print awareness and phonological awareness are related to the etiology of decoding can provide insights into the development of word reading. To address this issue, we examined the degree of overlap among etiological influences of prereading skills in 1,252 twin pairs in kindergarten. Genetic, shared environmental, and nonshared environmental factors were significant for all three literacy phenotypes. The majority of genetic and shared environmental influence on decoding was due to common factors that included print awareness and phonological awareness. Notably, only a single genetic factor contributed to all three literacy phenotypes, but there was additional shared environmental influence common to phonological awareness and decoding. Findings suggest commonalities in the etiology of prereading literacy skills that could inform work on the development of reading skill.     

Individual Differences in Young Children's Pretend Play with Mother and Sibling: Links to Relationships and Understanding of Other People's Feelings and Beliefs

50 33-month-old children were observed at home with their siblings and mothers. Observational measures of pretend play, observer ratings of the child's, mother's, and sibling's behavior, and measures of family discourse about feelings were collected. At 40 months each child was assessed on Bartsch and Wellman's false beliefs task and Denham's affective perspective taking task. Results revealed individual differences in the amount and sophistication of young children's social pretend play and suggested that these individual differences are related to experiences in the relationships that young children have with their mothers and siblings. Results also indicated that early social pretend play was significantly related to the child's developing understanding of other people's feelings and beliefs. The data are interpreted as providing support for the notion that early experience in social pretense is associated with children's mastery of the relation between mental life and real life. The importance of considering the relationship context of social pretense is also discussed.     

Nonshared environmental influences on individual differences in early behavioral development: a monozygotic twin differences study

The monozygotic (MZ) twin differences method was used to investigate nonshared environmental (NSE) influences independent of genetics. Four-year-old MZ twin pairs (N = 2,353) were assessed by their parents on 2 parenting measures (harsh parental discipline and negative parental feelings) and 4 behavioral measures (anxiety, prosocial behavior, hyperactivity, and conduct problems). Within-pair differences in parenting correlated significantly with MZ differences in behavior, with an average effect size of 3%. For the extreme 10% of the parenting-discordant and behavior-discordant distributions, the average NSE effect size was substantially greater (11%), suggesting a stronger NSE relationship for more discordant twins. NSE relationships were also stronger in higher risk environments, that is, families with lower socioeconomic status, greater family chaos, or greater maternal depression.