It owes something to PostgreSQL but it's the syntax, not the source code. I quote from https://en.wikipedia.org/wiki/SQLite#History

    Hipp based the syntax and semantics on those of PostgreSQL 6.5. In August 2000, version 1.0 of SQLite was released, with storage based on gdbm (GNU Database Manager).

According to these slides from Sqlite founder, Sqlite was a "spin-off" of Postgres: http://www.pgcon.org/2014/schedule/attachments/319_PGCon2014...

According to this, "SQLite was originally written from PostgreSQL 6.5 documentation" https://www.pgcon.org/2014/schedule/events/736.en.html

So, "fork" wasn't the right word. Apologies.

No. This is incorrect.