Discussions of sexual diversity in nature increase student sense of belonging in biology

Abstract Biological sex is a complex and highly variable trait; however, overly simplistic explanations are common in undergraduate biology classrooms. Here, we test the impact of an accurate approach to teaching about the diversity of biological sex in organismal biology (“treatment” lecture) and compare this approach to a “traditional” lecture section of the same introductory biology course. We show that (1) the treatment lecture has a positive impact on feelings of inclusion for LGBTQIA+ students, (2) the treatment lecture had a positive impact on LGBTQIA+ and TGNC (transgender and gender nonconforming) student experiences in the course compared to other students, (3) after the treatment lecture students were able to more accurately define sex and gender compared to the control section, and (4) regardless of treatment students reject the naturalistic fallacy. Results highlight the importance of teaching the diversity of biological sex in an accurate way and distinguishing sex from gender.