The nature of science in genetics education: a historical analysis of Japanese high school biology textbooks, 1963–2023

Background While international research has explored the Nature of Science (NOS) in textbooks, few studies have systematically analyzed its historical evolution within a specific subject area.Purpose This study investigates how NOS is represented in the genetics content of Japanese high school biology textbooks from 1963 to 2023.Method Using the ten-dimensional NOS framework by Abd-El-Khalick et al. (2017), we analyzed 14 textbooks published over the six-decade period.Results The representation of NOS followed a trajectory of initial growth, a sharp decline in the 1980s under the ‘Relaxed Education’ policy, and a recovery from the 1990s onward. Explicit-reflective (86%–95%) and content-embedded (79%–88%) approaches were predominant. The depth of genetics mechanisms evolved from simple definitions (e.g. mutation) to system-based explanations (e.g. DNA sequence changes and natural selection), emphasizing the Tentative, Theory-laden, and Inferential NOS dimensions. Additionally, portrayals of genetic discoveries shifted from linear narratives to multidimensional, socially embedded perspectives.Conclusions Historical curriculum reforms and advances in scientific knowledge jointly shaped the presentation of NOS in Japanese genetics education. These findings offer valuable insights for future curriculum design and NOS-integrated science education globally.