How would you ever know if you "have" perfect pitch without training? I don't even know what a C or B is[0]. Are there any tests online that don't require prior knowledge?
[0] I do realize they denote some frequencies
[0] I do realize they denote some frequencies
To answer your question, you won't. Perfect pitch usually develops in people who have had musical training since very young childhood. Just like you can't really remember learning your native language, they can't remember learning this skill. But like everyone, they did learn it at some point.
I was always taught there are 12 notes, while any standard scale contains only 7 of them. (The chromatic scale obviously being the exception which contains all 12.)
Accidentals are just for notation -- obviously B-flat and A-sharp are the same "note", just as F-sharp-sharp and G are.
Our entire turning of equal temperament is based on 12 equal intervals, not 7. So I'd argue parent commenter is correct -- notes are base 12, not base 7.
So...one could argue for either or both interpretation and explanation. The note names, sharps and flats, is what is most arbitrary about it.