Yours is the normal way to express the genetive in english van jou is the normal way to say it in dutch. Which is belonging to you or of "yours". (Not quite sure if it is of him or of his, people don't really seems to agree. Something like one is grammatically correct but never used and the other isn't really correct but almost exclusively used so becoming more correct than the other one...)
(In dutch there is jouwes but imo that is kiddie speech or dialect. Eventhough I think I saw it in the tips, in my view it isn't proper Dutch and sounds very uneducated. I would not advice using it.
Edit nvm there is no jouwes in the tips thank God. But de jouwe Which is a big step up but I still advise (die) van jou. De jouwe Sounds unusual stilted a weird mix of too educated and too uneducated. De jouwe reminds of jouwes,,but de zijne sounds overly regal at the same time) To some they may sound fine but van jou will sound good to everyone.)