The primary objective of this paper is to find out whether the genetic concepts conveyed by cinema could encourage students' personal misconceptions in this area. To that end, two sources of conceptions were compared: the students' personal concepts (from a consolidated bibliography and from an experimental sample) and the concepts conveyed by cinema. After categorising and analysing, the students' persistent preconceptions were compared with those conveyed by cinema. The study reveals that the concepts conveyed by films can reinforce students' misconceptions and become learning obstacles. Based on these results, implications for further practice are shown. We present a didactic proposal that begins with the explanation of the misconceptions and promotes a conceptual change.