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Intrinsic capacity (IC), which reflects the combined physical and mental reserve of an individual, is a key indicator of healthy ageing. While genetic and environmental factors influence IC, the interaction effects between them remain poorly understood. This study investigated the independent and interaction effects of polygenic scores for IC (PGS-IC), socioeconomic status, and lifestyle factors on IC. Baseline data from the Canadian Longitudinal Study on Aging (CLSA; N = 13,112) were analysed. Associations with IC (outcome) and interaction effects of PGS-IC and socioeconomic factors or lifestyle measures-including composite physical activity and diet scores-were examined using linear regression models. All models were adjusted for age and sex, and additionally for five genetic principal components in models involving PGS-IC. Higher IC was associated with higher education, income, physical activity, and healthier diet patterns. Lower IC was observed among previous and current smokers and those with short (<7h) or long (>9h) sleep durations. PGS-IC was positively associated with the IC score. Significant gene-environment interactions were identified between PGS-IC and; Mediterranean diet (β = -0.003, 95% CI: -0.006, -0.0002), education in younger adults (β = -0.109, 95% CI: -0.211, -0.007), and sleep duration (younger adults: long sleep, β = 0.198, 95% CI: 0.023, 0.373; older adults: short sleep, β = -0.095, 95% CI: -0.153, -0.036). This study provides preliminary evidence of gene-environment interactions influencing IC, with implications for future research to determine how genetic and modifiable factors can inform strategies for maintaining IC and promoting healthy aging.