The SARS-CoV-2 virus and its variants have had and are having serious implications for the mental health of the public. The critical limitations in the published literature for children, adolescents and young adults raise doubts about their clinical utility and overall generalisability. Amidst these gaps in knowledge, a twin study (Rimfeld et al) addresses several of these issues in relation to heritable individual differences and responses to environmental stressors. Besides calculating genetic correlation, the longitudinal study also compares symptoms at four different time points during the pandemic. These findings reflect a counterintuitive understanding of the role of resilience in the mental health of young adults in the UK. Unlike prior studies, this study focuses on methodological designs and underscores the applications of accurate statistical measures in observing these complex phenomena.