In a social system a sustainable coexistence is difficult to attain without generous interactions among its members. Generous interactions or generosity is liberality in spirit or act. Several studies have tried to find out some possible causes of generosity. Interestingly, some studies have suggested that gene might affect generosity. Again it has been concluded in some studies that religion is not necessary but it can make a substantial contribution towards generosity. So whatever may be the cause of generosity, we assume in this article that a person is generous. On the basis of this assumption we have developed a model and tested different cases. In this model a generous person gives quot;good thingsquot; to a disadvantaged person without considering latter's honesty. But if the generous person takes into account the honesty of the latter person, and feels regret for assisting him, then the model shows that a generous person may become quot;selectively generousquot;. However, this model needs empirical verifications before coming to any conclusion