Not invented here
Also known as NIH syndrome
Not invented here is rejecting or undervaluing ideas, products or knowledge because they came from outside your own team, company or group. It is common in organizations that take pride in their own work.
In everyday life
A software team spends months building its own tool instead of using a proven free one made by another company.
A chef refuses to try a prep technique a rival restaurant developed, insisting her kitchen will come up with something better, even though the rival's method is clearly faster.
Why your mind does this
Trusting people and things we know is usually safe, because familiarity means we have dealt with them before without harm. Favoring our own group helped our ancestors cooperate with the people they depended on. Liking what is close and known also saves the effort of judging everything from scratch.
Its family, in 30 seconds: Familiar is better
How to spot it
Notice when your first objection to a solution is where it came from.
How to counter it
Evaluate outside solutions against the same criteria you use for your own, ideally with the source hidden.
Same family: Familiar is better
SourcesKatz & Allen (1982)·Wikipedia