It is generally viewed as insular and unhealthy for academia.
[1] Intellectual inbreeding is thought to hinder the introduction of ideas from outside sources, just as genetic inbreeding hinders the introduction of new genes into a population.
[2] The Commission on Graduate Education in Economics (COGEE) recognizes it as "a trend for emulation rather than diversification."
Academic inbreeding has also been cited as a major problem in the major universities of the People's Republic of China—such as Peking University and Tsinghua University, which have adopted measures in recent years specifically to combat the practice[1][3]—and South Korea.
[4] A relevant study[5] also exists that analyzes the issue by considering Russia and Portugal as examples.