He was presumably raised the same way he's raising his sons. One generation of trauma and insanity begets another. If we saw WWJ as a young child, I'd be willing to bet that he was an innocent enough kid, or at least a non-evil. I get the sense that WWJ's dad was a strict and psychotic fundamentalist who drank heavily and showed WWJ little affection, resulting in him becoming so maladjusted and hedonistic.
In a strange sort of way, I pity WWJ. I definitely don't like him or sympathize with him, but I understand him. He's dead inside and he's filled with pain. He's like a rabid dog that needs to be put out of its misery.