Résumé
The purpose of this paper is to create and define a model for the effects of treatable, hereditary illnesses on human culture and biology based on the trends displayed by Cystic Fibrosis. This disease has passed through different stages during human history that can be characterized by a given status of the gene frequency and an associated attitude towards fertility held by families and individuals affected by the disease. With each stage there are characteristic attitudes resulting from different factors and these attitudes in turn lead to changes in gene frequencies. It is beyond the scope of this paper to quantify the movement of gene frequencies characterized by the Coevolutionary Shift Model. It is sufficient at this point to characterize these movements by intuitive, theoretical background and to correlate these movements with well-documented support for the corresponding attitudes towards fertility. Sickle Cell Anemia, Phenylketonuria, and Tay Sachs are also fitted to this model to determine if it applies widely to other diseases. Although they are not described to the extent that Cystic Fibrosis is, they help to further define and modify the model