An incestuous relationship is one involving sexual intercourse between two members of the same family, for example a father and daughter, or a brother and sister. They accused her of an incestuous relationship with her father
disapproval If you describe a group of people as incestuous, you disapprove of the fact that they are not interested in ideas or people from outside the group. Its inhabitants are a close and incestuous lot
What you might expect: code with knowledge of used code's internals beyond the API This breaks modularity, increases complexity and causes bugs, and a design goal is to minimise this behaviour