IN THE world of Harry Potter, Dudley Dursley, the boy wizard’s rotund and obnoxious cousin, turned 35 yesterday. 35?! Do you feel old, now?

In honour of the forever-hungry dunce, JK Rowling has given Potter fans a birthday present — the backstory to the Dursleys’ hostility towards Harry, the nephew they forced to live under the stairs.

Anyone familiar with the mega-franchise knows Aunt Petunia, Uncle Vernon and Cousin Dudley are small-minded and mean-spirited Muggles who figuratively tortured Harry when he was growing up, denying him any love and affection one would expect from family while treating him as a servant — but, you know, the kind that doesn’t get paid, which would technically make Harry a slave.

Rowling revealed, on her Pottermore website, that Harry was pretty much doomed to attract the Dursleys’ hostility since before he was conceived.

We already knew about Petunia’s disgust for all things magical since her ankle-biting days, likely born from jealousy of the ‘special’ gifts of her sister Lily, Harry’s mother. According to Rowling, when Vernon first met Harry’s parents, Lily and James, it wasn’t exactly what one would call an amicable exchange.

Rowling wrote: “James was amused by Vernon, and made the mistake of showing it.” Apparently, Vernon, being the kind of person who cared about such things, asked James what car he drove and James went on to describe the awesomeness of his broom. And when Vernon wondered out loud if wizards collected unemployment benefits, James countered back with Gringotts, the wizards’ bank.

Vernon couldn’t figure out if James was serious or if he was making fun of him. Thus, the hatred was seeded.

Petunia wouldn’t allow Lily to be her bridesmaid and the Dursleys boycotted the Potters’ wedding altogether. They even almost tore up Harry’s birth announcement.

So you can see why the uptight Dursleys were none-too-pleased to see an old man with a pointy hat and a hulking gamekeeper turn up at their door with their infant nephew.

Rowling also said that, like Snape’s dislike for Harry, Vernon loathed his nephew in part because he looked so much like his father. Which makes it at least the second time Harry became a victim of his dad’s douchebaggery to someone in the past.

Rowling also revealed that she almost gave Petunia a reprieve in the personality department in Deathly Hallows. She considered showing a softer side of Petunia in the goodbye scene but decided to keep the character consistent.