Summary: Current policy discourses demonstrate a weak connection to broader theoretical debates about family obligation and in particular how family responsibilities become negotiated over time and across the life course. How policy imagines family care can, therefore, be different to the actual experiences of families. This qualitative paper, using semi-structured interviews, explores the experience of a particularly neglected group, adult siblings, who have a brother or sister with autism (plus learning disability). We spoke to 21 adult siblings, met with 12 of their siblings with autism and talked to 12 health and social care professionals.

Findings: Our analysis suggests that connectedness and commitment, which remained subject to continuous redefinition by all family members, informed sibling relationships Practitioners, however, struggle to engage with this complexity, thereby undermining the extent siblings’ relationships can be realised.

Application: The paper concludes that policy initiatives are at risk of becoming an uneasy compromise, in which the need to offer choice occurs alongside the ‘problem’ of managing family care. Sibling relationships are more than simply ‘being of’ or ‘belonging to’ a family. They are dynamic, subject to contingency and negotiation. Interventions should be formulated to work with these assumptions, without presupposing a definite experience fixed in time and space. This would not only maximise the disabled siblings’ quality of life, but also ensure a more productive and fulfilling context for family relationships.