Research and opinion polls demonstrate that attitudes toward same-gender parent families have been improving in recent years among Western countries; however, the history of oppression toward, and misconceptions about, same-gender parent families continue to be demonstrated in Australian family rights policies. Common misconceptions include the belief that children need both male and female role models, and this could be influencing peoples’ support for same-gender family rights and having a wider impact on legislation change. Yet a dearth of research exists exploring a connection between gender role beliefs and support for same-gender family rights using a broad international sample, including Australia. To investigate this connection, a sample (N = 615) from 18 English-speaking countries responded to a series of questions to determine the importance of gender norm beliefs on same-gender family prejudice. Regression analysis demonstrated that people with traditional beliefs about gender norms were more likely to endorse a negative attitude toward same-gender marriage and same-gender parenting. Findings suggest a link between socially prescribed gender norms and prejudice toward same-gender parent families that may be fueling arguments against same-gender family rights policies. The implications of these findings on same-gender parent families and their rights require future investigation.