Recent studies on the learning of the science concepts indicate that most students have misconceptions of the science concepts. The misconceptions have their roots in the various aspects of teaching and learning situations. The textbooks used in schools have been substantiated as one of the sources of the misconceptions. Genetics has been recognized as one of the most difficult areas for high school students to learn. Therefore, this study had its objective to identify the misconceptions of genetics held by high school students and analyze the high school biology textbook as the source of the misconceptions. In order to indentify the misconceptions of the genetic concepts, the volunteer students were interviewed and genetic content and its sequence in the high school biology textbooks were analyzed. The misconceptions identified in this study are as follow: gamete formation, mitosis, trait expression, and allele and gene behavior in meiosis. This study found that the high school biology textbooks might be the source of those misconceptions. Based on the misconceptions identified, this study proposed direction for efficient instruction of genetics in high schools.