Nowhere are the principles of autonomy and privacy more frequently underscored than in the context of modern human genetics. Fear of untoward socioeconomic and psychosocial consequences of genetic knowledge has reinforced the need for medical confidentiality. However, genetic information is necessarily familial and the needs and interests of other family members cannot be ignored. The past decade has witnessed a gradual move away from the status quo position of absolute confidentiality, to an intermediary position of it being the duty of the patient, to a position making it ethically permissible for the physician to warn in certain limited circumstances. Founded on the principle of mutuality, this last position will revolutionize not only the physician-patient relationship but also the modern, nuclear family.