The condition of hereditary colorectal cancer (HNPCC) is an illness whose psychosocial consequences for those affected and their families are still poorly researched. Health behavior in the case of HNPCC means regular participation in a specific prevention and early detection program. Do HNPCC patients and their family members, who attend a genetic/clinical counseling session, actually take advantage of the recommended preventive measures? Additionally, the question arose regarding the influence of control and competence expectations, particularly the impact of self-efficacy, which seems to play a significant role in health behavior in general. However, the results indicate that this does not necessarily apply to the hereditary condition HNPCC. It also became clear that the counseling, in its current pathogenic orientation, does not significantly change the preventive behavior of the individuals seeking advice. Therefore, it is reasonable to conclude that future counseling should emphasize a salutogenic perspective more, in order to particularly support individuals in their expectations of self-efficacy.