Until December 2020, Spanish primary schools were not required to provide any kind of sexuality education, and most teachers did not receive training to carry it out. However, sexuality is clearly present in children's daily lives in school. We carried out qualitative research with teachers from four primary schools in Catalonia (Spain), aiming to explore how teachers without specific training in sexuality approach the issues in the classroom. Our analysis shows that teachers in the four schools governed children's sexuality in a gendered manner, using communicative vigilance and surveillance to regulate how children touched their own genitals. Findings suggest the need for continuing professional development and training to ensure teachers (re)think what adults may communicate to children about sexuality and gender when they have not received training in relationships and sex education.