He comes from a leafy part of rural Durham and his mum's wealthy - despite MaMa McKray claiming on Harry's eviction that her son is a 'humble working class Geordie, hard working plumber' etc. Jay's probably posher than Aaron
but not as posh as Harry (probably why Harry was chosen so he'd be the posho).
You see a "Geordie" accent hides a multitude of 'sins' (ie real class background etc)
Now I understand why he was annoyed that real Geordie Alex was in the house and hardly spoke to her for ages (she ruined his 'down to earth' Geordie USP).
Now I understand why he was able to afford a £50K car and a rather swanky flat, Armani T-shirts and jeans (despite claiming to be a humble plumber struggling for work).