There is a traditional concern, reinforced in a number of religious doctrines, at any tendency to "keep bad company" or to "associate with undesirables". In business and public life this translates into relationships which subvert formal roles to favour personal interests, whether financial, sexual, political or otherwise. Such relationships may involve threat, bribes or blackmail, whether on the frontiers of legality, in grey areas or in association with criminals. In private life it may involve relationships whose nature is concealed for fear of censure and because of the damage caused to other relationships. These may take the form of hurtful games between people, possibly involving some form of threat or manipulation. Such relationships are especially unhealthy when they appear normal, or even benevolent, with their true nature only emerging later in time. After all, a person is known by the company he or she keeps.