Clinical genetics has wrestled with the problem of misattributed paternity for decades. While there are no clear directives on policy, surveys suggest that genetics professionals are inclined to avoid disclosure when possible. Changes associated with the increased use of genomic testing will alter the context and may limit the benefits of non-disclosure. Multi-site testing will preclude the uncertainty often associated with single-gene testing. Increased use of genetic testing in clinical and non-clinical settings will create new opportunities for the subsequent unmasking of misattributed relationships, as will the presence of test results in the electronic medical record. Family health history information will become more valuable as it is used more often and to better effect in risk assessment, diagnosis, treatment and reproductive decision-making. These changes associated with genomic testing increase the risks and decrease the benefits associated with the nondisclosure of misattributed paternity. For ethical and practical reasons, genetics professionals, and those who advise them, should consider a greater emphasis on the value of carefully planned disclosure.