For science teachers using the discourse of socioscientific issues (SSI), it is important to make a decision as to whether when and how to disclose their own positions. The existing limited literature shows that science teachers prefer one of four roles during SSI discourse: sticker to facts, imposer, democracy advocator, and committed impartialist. The purpose of the present research is to understand the nature of preservice science teachers' (PST) beliefs underlying such selection. Based on existing literature, we developed a teacher's belief questionnaire including vignettes representing four teacher's roles in discussion of genetically modified (GM) foods. Three hundred twenty-four (324) PSTs from a Turkish context experiencing SSI-based reforms completed these questionnaires, selected one of the teacher's roles, and justified their selection by writing reasons. Content analysis procedures were used in data analysis of this qualitative study. The results show that most PSTs selected dialogical roles (democracy advocators and committed impartialists). Looking at their beliefs, epistemologies and teaching goals work together in PSTs' selection of their preferred role. In addition, we argue that there is no desired alignment between teachers' existing beliefs and expectations of SSI reforms. We conclude by indicating certain implications that may enhance such alignment.