Autism Spectrum Disorder (ASD) is a life-long condition which affects the individual and their family system. Little research understands the impact of an ASD upon families, how this may change over time and how COVID-19 has impacted these dynamics.To explore the impact of an ASD on the lived experiences of parents and neurotypical adult siblings, including during the UK COVID-19 lockdown.Eight parent-sibling dyads (16 individuals) completed semi-structured interviews discussing their family before, during and after receiving the ASD diagnosis, and in relation to the first UK lockdown. Interview transcripts were analysed using Interpretative Phenomenological Analysis.Three super-ordinate themes were identified: Dominated by ASD; Family Cohesion; and the Need for Support.The data suggested a closeness within the families and an adoration towards the individual with ASD (IWA). Dyads were, to an extent, consumed by the diagnosis both presently and in the future, implicating the need for a stretch in services to support parents and neurotypical siblings. In terms of the first UK lockdown, the IWA added an extra layer of difficulty to the dyads work-life balance yet there was an essence of family cohesion. Future research should consider longitudinal methods and explore the impact of ASD co-morbidities upon family dynamics.