Not invented here

Tendency to avoid things with an external origin.

Cause

It is usually adopted by social, corporate, or institutional cultures.

People may not use others' work for various reasons like, to support a local economy instead of paying royalties to a foreign license-holder, fear of patent infringement, lack of understanding of the foreign work, an unwillingness to acknowledge or value the work of others, jealousy, belief perseverance, or due to a wider turf war.

Consequences

In computer programming, "NIH syndrome" leads to the belief that in-house developments are better.