ERIC Number: EJ816076
Record Type: Journal
Publication Date: 2008-Nov
Abstractor: As Provided
Reference Count: 0
Developmental-Genetic Effects on Level and Change in Childhood Fears of Twins during Adolescence
Eaves, Lindon J.; Silberg, Judy L.
Journal of Child Psychology and Psychiatry, v49 n11 p1201-1210 Nov 2008
Background: If the adaptive significance of specific fears changes with age, the genetic contribution to individual differences may be lowest at the age of greatest salience. The roles of genes and environment in the developmental-genetic trajectory of five common childhood fears are explored in 1094 like-sex pairs of male and female monozygotic and dizygotic twins assessed on up to three occasions during adolescence (ages 8-18 years). Methods: Dichotomous self-ratings of a cluster of five correlated fears from Ollendick's schedule of fears (FSSC-R) were extracted for subjects at each occasion of assessment. The effects of genes and environment on overall level of fears and rates of adolescent decline were explored by fitting an item-response theory ("IRT") model that allowed for individual genetic and environmental differences in initial fear level ("intercept") and rates of adolescent change ("slope") across the repeated waves of measurement. Different forms of the model were explored using Markov Chain Monte Carlo (MCMC) methods to derive the posterior distribution of subject and item parameters from the raw responses. Results: Additive genetic differences affect the common factor underlying the five fear-items. The same genes also affect rates of change with age, especially in boys. Male adolescents with higher overall genetic predisposition to childhood fears tended to show slower recovery with age than subjects with relatively low initial values. Thus, the genetic variance apparently increases with age. Conclusions: This finding is consistent with a prediction that the regulation of genetic differences will be strongest, and thus the additive genetic variance will be smallest, at the age when the particular stimulus is most salient. Items differed in the extent to which they were sensitive to underlying random differences in the rate of developmental change. Individual differences in rates of change with age were more marked in boys than girls.
Descriptors: Twins, Markov Processes, Adolescents, Genetics, Fear, Measures (Individuals), Individual Differences, Developmental Stages, Item Response Theory, Monte Carlo Methods, Gender Differences
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Authoring Institution: N/A