Background and aims: The association between perceived stress (PS) and gaming addiction (GA) is well documented. However, the mechanism for explaining this association remains unclear. Using a genetically informative design, this study aims to distinguish between the diathesis-stress and bioecological models of gene by environment interaction (G x E) to explain the underlying mechanism of the relationship. Methods: In total, 1,468 twins (mean age 5 22.6 +- 2.8 years) completed an online survey including the GA and PS scales. Twin correlations for GA and PS were computed and univariate model-fitting analysis was conducted to determine genetic and environmental influences on GA and PS. The bivariate G x E model-fitting analysis was performed to determine the best G x E interaction model. Results: Additive genetic, shared environmental, and non-shared environmental effects were 0.70 (95%CI 5 0.61, 0.77), 0.00, and 0.30 (95%CI 5 0.26, 0.33), and 0.38 (95%CI 5 0.24, 0.55), 0.35 (95% CI 5 0.18, 0.51), and 0.22 (95%CI 5 0.20, 0.26) for GA and PS, respectively. Bivariate G x E modelfitting analysis supported the diathesis-stress model, where genetic influences on GA were greater in higher levels of PS, whereas environmental influences on GA were small and constant across levels of PS. Discussion and conclusions: The evidence for the diathesis-stress model for GA is consistent with the etiological process of many forms of psychopathology. The findings should be incorporated in clinical settings to improve the treatment of GA, and used in developments of intervention and prevention methods for GA.  Kulcsszavak: gaming addiction, perceived stress, diathesis-stress model, twins, genetic vulnerability