So here's a theory...
Note I am placing this in the concept boards as it is a concept about a champion and technically doesn't fit anywhere else except miscellaneous or general discussion.
Before I start I'll slightly sum up this in that I think there is more to Jinx being crazy than it would appear.
So I recently discovered the QnA about Ekko and lots of people seem to believe that Jinx/Vi are related To Ekko for more reasons than being from Zaun (probably cause it says on Jinx's Leaguewiki page that Ekko had a crush on her). For instance one person asked if Ekko drew the entirety of the mural that is shown in his reveal trailer and the answer was in fact no, with the reason being that it was more a communal painting with multiple artists. specifically this is the response given by a Rioter:
Parts of it, definitely. Like in other urban cities where violence/accidents claim lives, these street memorials are very communal, often with many contributors. Lots of people lose those they love.
See what's interesting here is that 
has a quote stating,
_ "You think I'm crazy? You should see my sister."_
that, I feel, is often misinterpreted to mean that Vi could be her sister or that the sister in question has yet to become a champion.
However what I think is the truth is that the blue haired girl in the mural was who Jinx was and something made her own sister die and Jinx go nuts. So now her "old self" died with the real dead sister that is talked about, and the Jinx we know is an alternate personality/crazed lunatic that thinks shes the sane one of the pair (even though there's only actually one sister left). This might also be helped by Jinx having the technology to both blow things up and also shrink them down (at least in regards to her guns) which one could have been something the other sister had been working on and the survivor adopted as her own research.
Anyway anyone who wants to post their own opinions about this please do so. I'd love to discuss this with people and see who else thinks it might be true!
