This study integrates criminological social learning and psychological explanations of individual factors and mechanisms for science denial to offer an individual-level analysis of ‘alternative lifestyle’ subcultural groups in cyberspace in order to understand the assimilation, success and proliferation of potentially dangerous health-related misinformation. Through a rigorous passive online ethnography of two relevant self-identifying ‘alternative lifestyle’ Italian- and English-speaking online communities observed over the initial stages of the COVID-19 pandemic, we observed the unfolding of online narratives and behavioural intentions of criminological and psychological interest. We identified in our data both individual factors and mechanisms for science denial and clues to social learning, and we showed how they interrelate. Furthermore, by looking at the linguistic and visual resources used to shape how participants think through social learning mechanisms, we identified four main narrative frames: informative; oppositional; empathetic; and agency and spirituality. The findings of this study provide a more comprehensive understanding of the reasons for and mechanisms behind medical misinformation online and suggest ways to mitigate the related harms.