Is JF-17 a reconfigured Mig-21/F-7?
One peculiarity was that the Pakistanis had a clause in their agreement with the Chinese that the JF-17 not be an F-7/Super 7 upgrade. Yet, the similarities to the Super 7 are quite obvious. If not actually based on the Super 7, then there is at least some commonality of design philosophy.

The truth is, it's impossible to tell. However, even if far back in it's genes there is still elements of the MiG-21 that wouldn't be so extraordinary. The F-18 if you go back, has parts of the F-5, which itself was based upon a 1950s fighter, the N156! As a slight twist, the Super 7 has elements of the F-20 Tigershark, which is an updated F-5.