In 1994, the Committee on Assessing Genetic Risks of the Institute of Medicine published their recommendations regarding the ethical issues raised by advances in genetics. One of the Committee's recommendations was to inform women when test results revealed misattributed paternity, but not to disclose this information to the women's partners. The Committee's reason for withholding such information was that "genetic testing should not be used in ways that disrupt families". In this paper, I argue that the Committee's conclusion in favour of non-disclosure to the male partner is unethical. I argue that both parties ought to be informed.