Padme cheats on Anakin with Jar Jar. Result of this "unholy bond" are two children, Luke and Leia Bings (who will afterwards be given the name"Skywalker" to avoid any diplomatic issues between the people of Naboo and the Gungans). Joda reveals this terrible secret to Anakin, who furius as he becomes, turns to the Dark Side to take revenge from Jar Jar. Anakin is killed in the fight, and Jar Jar becomes Palpatines apprentice to take Anakin's place as Darth Vader.
Jar Jar is furius with Joda telling the secret to Anakin and turns against the Jedi counsil, killing every single Jedi except Joda and Obi Wan who manage to escape. He then discovers that the Jedi were planning to constuct the Death Star and take over the repuplic. He steals the plans and gives it to the supreme chancellor who decides to construct this Space Station to protect the republic from the Jedi.
But Joda and Obi Wan conceive another evil plan: They kidnap Padme's children. The boy and the gilr are raised under their supervision, given the belief that the republic has turned into an evil emipire, so they can in time fight against it, and revive the Jedi faith and their evil dominion.

Edit: Note that my version is in full accordance with Rebel's 11_38 version, of which I am very fond!