When Jinx was born, everything was perfect. she had a happy life. she even got everything she ever wanted .
Until one day, she found a pretty pink stone that contain "bad luck" and thought it was pretty then picked it up with her's unicorn magic.
but unfounately, the stone corrupted her and transfered all the "bad luck" into Jinx by unicorn magic
Nothing happened to her at first then few days passed by thats when everything strange is going on, either everything had disappeared or destroyed.
Of course, everypony drove her out of the Canterlot due to "bad luck" so she had no other choice but to go into Ponyville and start a new life there.
But, thats when even stranger things happened.
Everytime she came across a building, it would collapsed.
Everytime she came across the pony, that pony would had bad luck for his/her life time.
So, she got tired of seeing everypony is afraid of her and become a villian in hoping she would destroy the world/everything but later she have been reformed by Twilight Sparkle