From this brief preamble, it is opportune to investigate how sexual education is taught in schools as well as the production of researchers engaged in studying this matter. Teachers are the main agents involved in the mediation of knowledge. After all, they mediate contents and discuss information on sex and sexuality that come from the family, society or media, with which children and adolescents interact. This study aims to investigate, from a selection of productions available on Capes Journal Portal, which are the theorists/theories most cited by researchers who discuss the teaching of sex and sexuality to children and adolescents. To identify the theoretical sources used by these authors to support their studies, the following research question was formulated: according to the authors that discuss sexuality education for adolescents and children, what are the characteristics of the teacher education program and which theorists are more cited in their studies? The study consists of a qualitative-convergent mixed systematic review. We used the descriptors ‘sexuality’ and ‘teaching’ in exact terms. The eligibility criteria consisted of articles (i) published from 2019 to 2020; (ii) with open access; (iii) reviewed by; and (iv) with a focus of interest on basic education (adolescents and children). The content analysis of the main results obtained allowed to organize the findings into four categories: school-based sexual education and teacher training: contributions to an inevitable discussion; teaching and sexuality; teacher training for sexuality education; theories cited. From the results, it can be seen that the mediation between the two theories – teaching and sexuality – takes place almost exclusively in Biology and Sciences classes. And in these subjects, the teachers’ focus is on reproductive issues, something that does not allow an effective exploration of the sexuality topic by the main players of the teaching action.