ObjectivesHereditary cancer has implications not only for patients but also for their at-risk relatives (ARRs). In current clinical practice, risk disclosure to ARRs involves collaboration between patients and healthcare providers (HCPs). However, the specific responsibilities of each party are intertwined and at times unclear. In this study, we explored public attitudes regarding moral and legal responsibilities to disclose familial risk information to uninformed ARRs.DesignIn an online cross-sectional survey, participants were prompted with a hypothetical scenario where a gender-neutral patient learnt about their familial risk of colorectal cancer. The patient was advised to regularly undergo colonoscopy screening, and this recommendation was extended to both their siblings and cousins. While the patient informed their siblings, they had not spoken to their cousins in 20 years and did not want to contact them. The survey assessed respondents’ views on the patient’s and HCPs’ ethical responsibility and legal obligation to inform the cousins (ARRs).ParticipantsA random selection of 1800 Swedish citizens 18–74 years of age were invited. Out of those, 914 (51%) completed the questionnaire.ResultsIn total, 75% believed that HCPs had a moral responsibility to inform ARRs, while 59% ascribed this moral responsibility to the patient. When asked about the ultimate responsibility for risk disclosure to ARRs, 71% placed this responsibility with HCPs. Additionally, 66% believed that HCPs should have a legal obligation to inform ARRs, while only 21% thought the patient should have such an obligation. When prompted about a scenario in which the patient actively opposed risk disclosure, a majority believed that HCPs should still inform the ARRs.ConclusionOur study indicates that the Swedish public ascribes moral responsibility for informing ARRs to both the patient and HCPs. However, contrary to current practice, they believe HCPs hold the ultimate responsibility. The majority of respondents support disclosure even without patient consent.