I am going to take issue with your use of ORM in this context. ORM is an acronym for Object Role Modeling, a modeling technique and model query language. ORM is base on semantic conceptual data modeling and business rule validation and has its own set of graphical notation. It is arguably the most powerful modeling method to capture rules, restraints and relations and has been around for a long time see http://www.orm.net

The use or ORM for object/relation mapping should be called Object Data Mapping since the objects know nothing of relations to any other object. Data elements in objects are supposed to be encapsulated, free of dependencies.