1. Objectifs

Intentions :
«[T]he first objective of the present study was to model the genetic and (shared and nonshared) environmental influences on gambling involvement and on substance use during early adolescence. The second objective of the present study was to examine the extent to which gambling involvement and substance use during early adolescence can be explained by the same underlying genetic, shared, and nonshared environmental factors.» (p. 348)

Questions/Hypothèses :
«[A] first important question that needs to be addressed is whether the relative contributions of genetic, shared and nonshared environmental factors to early adolescent gambling involvement are similar to those found for early substance use. A second, equally important question is whether the same genetic, shared and nonshared environmental factors that influence early gambling involvement also influence early substance use.» (p. 348)

2. Méthode

Échantillon/Matériau :
«The sample is part of an ongoing longitudinal study of a population-based sample of twins drawn from the Quebec Newborn Twin Registry of all twin births occurring in the Province of Quebec, Canada, between 1996 and 1998. A total of 650 families agreed to participate in the study.» (p. 348)

Instruments :
Questionnaire

Type de traitement des données :
Analyse statistique

3. Résumé

«A general absence of parental norms or family rules that discourage gambling in most families may thus explain why environmental factors shared by twins raised together did not significantly account for interindividual differences in early gambling involvement in the present study. In contrast, the likely greater variability of family rules regarding substance use—with very lenient rules in some families and very strict rules in other families—may explain why shared environmental factors contributed to substance use during early adolescence in the present study.» (p. 353), mais ajoutent également que «future research should include contextual measures such as peer group or family norms, which could play an important role for conditioning the expression of genetic liability. The contribution of these variables may vary across development, because the genetic-environmental architecture of both gambling involvement and substance use could change with age as adolescents become more autonomous and as problem behaviors become more normative or more specialized (Vrieze et al. 2012).» (p. 353)