Teachers are key players in supporting the understanding of epistemological and social aspects affecting the development and validation of scientific knowledge, but they often hold inappropriate views of the Nature of Science (NOS), therefore hindering this understanding as an essential part of students' scientific literacy. To tackle this challenge from the initial teacher education level, an innovative inquiry-based intervention contextualised in the scientific controversy of spontaneous generation has been developed and evaluated by involving pre-service teachers. Results from a pretest/posttest-control group design showed improvements in the understanding of the epistemological and sociological aspects after the intervention. The effect size detected in the experimental group versus the control group was retained and even enhanced five-and-a-half months after its completion. These results are especially relevant to respond to experts' claims about the need for further studies to understand the issues related to retention following explicit instructions about NOS. Additionally, qualitative data provided an enriched picture of the participants' understanding of the NOS, unveiling the complexities of the different issues involved and suggesting the need to combine quantitative and qualitative studies. Finally, implications for teacher educators and educational researchers are presented along with directions for future work in the field.