This article investigates a high-profile and ongoing dilemma for healthcare professionals (HCPs), namely whether the existence of a (legal) duty of care to genetic relatives of a patient is a help or a hindrance in deciding what to do in cases where a patient’s genetic information may have relevance to the health of the patient’s family members. The English case ABC v St George’s Healthcare NHS Trust and others considered if a duty of confidentiality owed to the patient and a putative duty of care to the patient’s close relatives could coexist in this context. This article examines whether embracing the concept of coexisting duties could enable HCPs to respect duties in line with their clinical judgement, thereby providing legal support and clarity to professionals to allow them to provide the best possible genetics service to both the patient and their family. We argue that these dual duties, framed as a novel, composite duty to consider the interests of genetic relatives, could allow HCPs to exercise and act on their professional judgements about the relative value of information to family members, without fears of liability for negligence or breach of confidence.