Genetic information is relevant not only to the patient, but also to their family. Where a patient refuses to share that information with family members, then their legal rights may conflict. This paper focuses on that conflict between the rights of individuals and the rights of third parties. We first examine the nature of the duty of confidence as it applies in these circumstances, and the extent to which it can appropriately accommodate the familial nature of genetic information. We then consider the situations in which a healthcare practitioner might owe a third-party family member a tortious duty of care. We conclude that in most cases, there will be no duty owed to third parties, but that in certain limited circumstances, a duty of care should arise.