Since genetic information has implications for family members, some choices about genetic risk may be influenced by perceptions of responsibility to relatives. Drawing upon 25 semi-structured interviews with test recipients in Canada, this study explored decisions about inherited breast-ovarian and colon cancer. Qualitative data analysis revealed the pervasive significance of genetic responsibility in test decisions. We highlight three dimensions of genetic responsibility: 1) to know about the self for self; 2) to know about the self for others; 3) to know about the self to oblige others to know. It is argued that these dimensions of genetic responsibility have implications for test decisions, family relationships and other family members' desire to know (or not know) and to act (or not act) with respect to their own genetic risk. In particular, genetic responsibility may play out as a framing of a relative's moral obligation to know their risk that could obviate any interest they might have in not knowing. We conclude that perceptions of responsibility to—and of−other family members be thoroughly explored in genetic counseling sessions.