Sex Differences in Genetic and Environmental Influences on Age at Initiation of Gaming

The link between age at initiation of gaming (AAIG) and gaming addiction (GA) is well established, but the genetic and environmental etiology of AAIG remains poorly understood due to the scarcity of genetically informative studies. This study investigated genetic and environmental influences on AAIG using data from 1,394 South Korean adult twins (mean age = 23.0 ± 2.6 years; range = 19 to 30 years). Tetrachoric correlations for AAIG were 0.96 (95% CI = 0.92, 0.98) for monozygotic (MZ) male, 0.84 (95% CI = 0.69, 0.92) for dizygotic (DZ) male, 0.80 (95% CI = 0.73, 0.85) for MZ female, 0.56 (95% CI = 0.38, 0.70) for DZ female, and 0.54 (95% CI = 0.36, 0.68) for opposite-sex DZ twins. Mo\del-fitting analysis incorporating sex differences revealed that shared environmental factors dominated (71%; 95% CI = 39%, 89%), with a smaller but significant genetic component (24%; 95% CI = 6%, 57%) in males, whereas genetic factors played a larger role (59%; 95% CI = 37%, 77%), while shared environmental (21%; 95% CI = 5%, 41%) and non-shared environmental influences (20%; 95% CI = 15%, 27%) were also significant in females. Our findings highlight sex differences in genetic and shared environmental influences in the etiology of AAIG. Effective prevention and intervention strategies for GA should consider genetic vulnerability to AAIG and family exposures, incorporating sex-specific approaches.