This paper takes the position that the discourses of science and morality are not distinct within biology education; rather, they inform each other to produce, discipline, and regulate human sexuality. Our analysis of the medical and moral discussion on sexuality in a secondary school science textbook (the 12th standard National Council for Educational Research and Training textbook), along with insights from interviews with teachers, reveals that the texts portray a romanticized notion of sex that is limited to a monogamous heterosexual relationship. In the first part of the paper, we analyze how the biology textbook discusses “safer sex” in the limited context of sexually transmitted diseases and how scientific knowledge produces specific sexual subjectivities and categories. In our view, the portrayal of “normal sex” in the textbook is value-laden and not inconsequential. We also examine the discursive devices employed by the textbook to assert what is considered “culturally appropriate.” The second part of the paper focuses on interviews with three biology teachers from Keralam, India. Discourse analysis is used as a methodology to explore how teachers occasionally use scientific and moral arguments interchangeably. We discuss some examples where teachers use cultural and moral ideals to justify the scientific claims in the textbook. For instance, when the textbook focuses on how “promiscuity” produces disease, teachers emphasize how promiscuity can lead to sexual anarchy, fatherless children, unsatisfied spouses, and broken relations. We argue that the teachers, along with the textbook, intertwine scientific facts with moral sensibilities, articulating a view of science, technology, and medicine that aligns with socio-cultural norms.