>>45537422>>45536670Daughter of yakuza boss is a common anime and manga archetype. Sometimes these characters are depicted as shy and gentle, and then the expectations are subverted by revealing their family or business (the so-called "gap moe"). Judging from Erika's behaviour and appearance she may be based on this kind of character. Or she may be some miko-like character, who knows.
It has to be mentioned that Celadon is based on commercial district of Tokyo and it's ridden with Team Rocket who use a casino as their HQ. And in submerged in crime city like this there's a place that is off limits to guys and where a girl is the boss.
Connecting these two observation allows to speculate about her origins. There are no direct evidence just like with many things in Gen 1 (Green's Raticate, Team Rocket's involvement in Mewtwo creation and Giovanni's true goals, etc) but it's definitely not worse than the Ghost Gym leader theory (just a sprite error in my opinion).