Shortcomings in sex and relationship education (SRE) related to norms and lesbian, gay, bisexual, transgender, queer, intersex, asexuality (LGBTQIA) perspectives have been reported internationally and in Sweden. This paper reports on findings from a critical study of SRE content in Swedish biology textbooks for 13- to 16-year-old pupils, with the aim of revealing which sexual orientations and bodies are made visible or invisible in the texts. About 200 quotations were selected and analysed, quantitatively and qualitatively, with a focus on limitations and possibilities. The results show that LGBT content is visible in all SRE chapters. However, sexual orientation is often constructed as fixed. Furthermore, stereotypical gender binaries are reinforced via heteronormative assumptions regarding hormones, genitals and reproduction, focusing on differences instead of similarities, and thus limiting the‌ potential to widen non-binary perceptions of bodies and sexualities. Our quantitative analyses reveal that there are few, if any, queer, intersex, asexual or crip/disability representations. If gaps in young people’s knowledge regarding norms, intersex, asexuality, queer and crip sexualities are to be filled in order to promote equality and diversity, it is important to rethink the SRE content of Swedish biology textbooks.