Personal theories of inheritance, coping strategies, risk perception and engagement in hereditary non-polyposis colon cancer families offered genetic testing.

From the geneticist's (or 'genetic counsellor's') perspective, lay models of inheritance can be perceived as problematic because they might interfere with understanding and acceptance of the explanation of inheritance provided in genetic counselling. The work presented here forms part of a larger qualitative grounded-theory study where the aim was to develop theory that could explain variations in adjustment to genetic testing for hereditary non-polyposis colon cancer (HNPCC). Ten of the 29 individuals interviewed who were at 50% or 25% risk used a 'personal theory of inheritance' to justify or explain a belief that they did, or did not, carry the family mutation. Two others indicated that, as a coping strategy, they chose to believe themselves to be carriers. This article presents part of the theory of engagement that was constructed using this data, relating to the process of development of risk perception. The theory suggests that for some individuals, these beliefs can form part of a process of coping and coming to terms with risk. An exploration of these processes may help practitioners to better understand the complexity of risk perception in individuals at genetic risk for cancer, particularly those preparing for predictive test results. Further development and testing of the theory is discussed.