The Genetic and Environmental Etiology of Shyness Through Childhood
The objective of this study was to examine the genetic and environmental contributions to shyness throughout the school-age period. Participants were 553 twin pairs from the ongoing prospective longitudinal Quebec Newborn Twin Study. Teacher-rated measures of shyness were collected at five time-points from age 6–12 years. On average, shyness was moderately stable over time (r = 0.23–0.33) and this stability was almost entirely accounted for by genetic factors. Genetic factors at age 6 accounted for 44% of individual differences and these early genetic factors also explained individual differences at all subsequent ages (6–22%). Non-shared environmental factors explained most of individual differences at single time-points (51–63%), and did not account for stability in shyness. Contributions of shared environment were not significant. Our results suggest that the stability in shyness is mostly accounted for by early and persistent genetic contributions.
KeywordsShyness Development Longitudinal study School-age Twins
We gratefully acknowledge the on-going contribution of families, children and teachers in the Quebec Newborn Twin Study (QNTS). We also thank Hélène Paradis for data preparation and Marie-Élyse Bertrand for project coordination.
The present study was supported by the Social Sciences and Humanities Research Council of Canada (Grant No. 309262) studentship to Geneviève Morneau-Vaillancourt. The Quebec Newborn Twin Study (QNTS) is supported by the Social Sciences and Humanities Research Council of Canada, the Canadian Institutes of Health Research, the Fonds Québécois de la Recherche sur la Société et la Culture (multiple grants).
Compliance with ethical standards
Conflict of interest
Geneviève Morneau-Vaillancourt, Ginette Dionne, Mara Brendgen, Frank Vitaro, Bei Feng, Jeffrey Henry, Nadine Forget-Dubois, Richard Tremblay, Michel Boivin have declared that they have no conflict of interest.
All procedures performed in this study were in accordance with the ethical standards of Université Laval and Sainte-Justine Hospital and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants or their parents in the study.
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