Where did C-3PO's fussy and worry-prone personality come from?

Droids develop personality with their experience memory. Purging the memory should clear the personality, too. Unfortunately, this didn't work on C-3PO. It looks like this personality is hardwired to him. In the prequel trilogy, he was fussy and error-prone. In the original trilogy, he was again fussy and error-prone despite having memory wipe.

If you look at the first version of C-3PO, you'll found that he had the same personality even that time. This brings the question: From where did Anakin get this fussy and error-prone personality data to burn it as fail-safe default of C-3PO?