For over a century, genetic arguments for the existence of racial inequality have been used to oppose policies that promote social equality. And, over that same time period, American biology textbooks have repeatedly discussed genetic differences between races. This experiment tests whether racial terminology in the biology curriculum causes adolescents to develop genetic beliefs about racial difference, thereby affecting prejudice. Individual students (N = 135, grades 7–9) were randomly assigned within their classrooms to learn either from: (i) four text‐based lessons discussing racial differences in skeletal structure and the prevalence of genetic disease (racial condition); or (ii) an identical curriculum lacking racial terminology (nonracial condition). Over 3‐months that coincided with this learning, students in the racial condition grew significantly more in their perception of the amount of genetic variation between races relative to students in the nonracial condition. Furthermore, those in the racial condition grew in their belief that races differ in intelligence for genetic reasons significantly more than those in the nonracial condition. And, compared to the nonracial condition, students in the racial condition became significantly less interested in socializing across racial lines and less supportive of policies that reduce racial inequality in education. These findings show how biology education sustains racial inequality, and conversely, how human genetic variation education could be designed to reduce genetically based racism. © 2016 Wiley Periodicals, Inc. J Res Sci Teach 54: 379–411, 2017