Abstract
Disentangling the genetic and environmental influences of gambling is important for explaining the roots of individual differences in gambling behavior and providing guidance for precaution and intervention, but we are unaware of any comprehensive and systematic quantitative meta-analysis. We systematically identified 18 twin studies on gambling in the meta-analysis. The correlation coefficients within monozygotic (MZ) and dizygotic (DZ) twins, along with the corresponding sample size, were used to calculate the proportion of the total variance accounted for by additive genes (A), dominant genes (D), the shared environment (C), and the non-shared environment plus measurement error (E). We further assessed the moderating effects of gambling assessment (symptom oriented assessment vs. behavior oriented assessment), age, and sex. The whole sample analyses showed moderate additive genetic (a2 = 0.50) and non-shared environmental influences (e2 = 0.50) on gambling. The magnitude of the genetic influence (a2) was higher for disordered gambling assessed with symptom oriented assessment (53%) than for general gambling assessed with behavior oriented assessment (41%). Additionally, the magnitude of the genetic influence (a2) was higher for adults (53%) than adolescents (42%). Genetic influence (a2) was greater for male (47%) gambling than female (28%) gambling. Shared environment had noticeable effects on female gambling (c2 = 14%) but zero effect on male gambling. In conclusion, gambling behavior was moderately heritable and moderately influenced by non-shared environmental factors. Gambling assessment, age, and sex significantly moderated the magnitude of genetic and environmental influences on gambling. Note that the number of studies might serve as a limitation.
Highlights
Game-based gambling dates far back in human history as an almost universal activity, in that about 70–90% of people gamble at some time in their lives (Shaffer et al, 1999; Welte et al, 2014)
Slutske and Richmond-Rakerd (2014) found that gambling was influenced by both non-shared and shared environmental factors and that genetic factors played a negligible role in the occurrence of gambling
Because addiction is often largely influenced by genetic factors (Agrawal and Lynskey, 2008; Li and Burmeister, 2009; Agrawal et al, 2012), we further explored the potential moderation effect of gambling assessment to examine the difference in heritability
Summary
Game-based gambling dates far back in human history as an almost universal activity, in that about 70–90% of people gamble at some time in their lives (Shaffer et al, 1999; Welte et al, 2014). Prior research has attempted to determine the relative roles of genetic and environmental factors in gambling (Eisen et al, 1998; Winters and Rich, 1998; Potenza et al, 2005; Anokhin et al, 2009; Slutske et al, 2009, 2011, 2013; Beaver et al, 2010; Giddens et al, 2011; Blanco et al, 2012; Tuvblad et al, 2013; RichmondRakerd et al, 2014; Slutske and Richmond-Rakerd, 2014; Vitaro et al, 2014; Xian et al, 2014) and some reviews qualitatively summarized the related twin studies of gambling (Shah et al, 2005; Gyollai et al, 2013); we are unaware of any comprehensive and systemic quantitative meta-analysis. A small proportion of studies indicated that gambling is primarily influenced by genetic factors. Slutske and Richmond-Rakerd (2014) found that gambling was influenced by both non-shared and shared environmental factors and that genetic factors played a negligible role in the occurrence of gambling
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