One study demonstrated that injunctive norms (whether individuals perceive that others think they should perform the behaviour) were the strongest predictor of the prostate specific antigen (PSA) test (for prostate cancer) and colon cancer screening intentions; injunctive norms were also a significant predictor of intentions to get a mammogram (Smith-McLallen & Fishbein, 2008; Stok et al., 2014). The gene discussed is KLK3; the disease is colonic neoplasm.