Research has commonly explored siblings of people with disabilities’ roles in care for their brothers or sisters with disabilities. Social policy has also commonly framed young adult siblings of people with disabilities as ‘young carers’. However, there has been less consideration of the implications of care for the relationship shared between young adult siblings with and without disabilities and of what this may mean for social policy. What do different types of care mean for sibling relationships? What are the relational and social policy implications of care between siblings? Drawing on a qualitative study of 25 siblings with disabilities and 21 siblings without disabilities aged 15–29, this article explores how young adult siblings perceive, talk and act with regard to the different types of care enacted between them. The article identifies how, during young adulthood, some types of care can endanger siblings’ capacity to feel like siblings and discusses ways that young adult siblings talk and act in order to – as best they can – keep their role within the bounds of a normative sibling relationship. The findings are discussed in light of implications for social policy, particularly with regard to seeing siblings of people with disabilities as ‘young carers’.