Genetic testing for BRCA genes, associated with hereditary breast-ovarian cancer risk, is an accepted cancer control strategy. BRCA genetic testing has both medical and psychosocial implications for individuals seeking testing and their family members. However, promoting open and adaptive communication about cancer risk in the family is challenging for parents of minor children. Using prospective data collected from mothers undergoing BRCA genetic testing and their untested co-parents (N = 102 parenting dyads), we examined how maternal and co-parent characteristics independently and conjointly influenced the overall quality of parent–child communication with minor children. Statistical associations were tested in accordance with the Actor–Partner Interdependence Model. Significant Actor effects were observed among mothers, such that open parent–child communication prior to genetic testing was positively associated with open communication 6 months following receipt of genetic test results; and among co-parents, more open parent–child communication at baseline and greater perceived quality of the parenting relationship were associated with more open parent–child communication at follow-up. Partner effects were also observed: co-parents’ baseline communication and confidence in their ability to communicate with their minor children about genetic testing was positively associated with open maternal parent– child communication at follow-up. These results demonstrate that for families facing the prospect of cancer genetic testing, perceptions and behaviors of both members of child-rearing couples have important implications for the overall quality of communication with their minor children, including communication about cancer risk.