Virtual reality (VR) has gained prominence and a growing prevalence. However, parental attitudes toward using VR for educational purposes (i.e., educational VR (EVR)) are under-researched. This study investigates parents' perceptions and experiences regarding the use of EVR, focussing on mathematics learning. Using the technology acceptance model (TAM) as a guiding framework, qualitative interviews with parents and their children from ten families (15 interviewees) were conducted. The participants interacted with a VR serious game, solving 12 mathematical problems, followed by interviews. Qualitative data analysis reveals four main factors influencing parents' acceptance of educational VR: cognitive-developmental, affective-physical, technical, and contextual/chronological aspects. The original TAM's positive factors (usefulness and ease) are validated, while this study extends the model to include new positive (e.g., interest) and negative factors (e.g., health risks) specific to VR. Novel contributions to the literature include controversial factors (e.g., preference for 2D or 3D and mental effects) and positive factors (e.g., pandemic context, parent-child perspectives, and manipulatives). These findings not only contribute to the advancement of theory in EVR acceptance, but also provide valuable information for EVR design, parental involvement in educational initiatives, and informing educators and policymakers about diverse perspectives on educational technology.