As computing educators begin to recognize that their students need strong ethical foundations, there is a growing interest to integrate meaningful ethics education into undergraduate computing curricula. To achieve this, it is crucial to understand how students respond to ethical interventions in the classroom. This review examines the acceptance of ethical interventions in undergraduate computing courses, using the realist synthesis method to identify and refine underlying theories of student acceptance, and refine them through available studies. Four theories were identified in a synthesis of 13 reports, providing insight into what may improve student attitudes towards ethical interventions in which contexts and under which circumstances. The findings of this realist review offer guidance to intervention designers, researchers, and educators seeking to meaningfully engage students with ethics in computing education.