I believe with the fan theory that the reason the Dursleys were such jerks was that they had been living with a Horcrux for 11 years, Rowling said that wasn’t her idea, but she really liked it. Point is, I think she’d admit if she didn’t think of something this good.

That’s what I plan on doing if I ever write a novel: leave a lot of open ended questions and vague hints, let the fans come up with complex theories, then choose the best one and pretend it was my plan all along.

Anyone else suspect that, somewhere, Rowling is like, “Oh shit, I never thought about that before... I mean, yup, that’s it! Good for you! You guys figured it out! I was eventually going to tweet it, anyway.”