I don't care about that study; it sounds ridiculous. But I was reading this article and thinking about the primary thing that always struck me about Rowling's novels -- there's a fuckload of racism and prejudice. Like, probably more than any other children's book ever. Someone is getting discriminated against or put down for being different on essentially every page.
I have long thought that the concept of mudblood/pureblood being the central conflict of a secret wizarding society is easily her most interesting contribution to fantasy canon. I actually was always disappointed that, having established this atmosphere steeped in racism etc throughout her books, the climax has nothing to do with it. It's about love. Fuck love. Those books could have been a lot more than they were. Maybe I've reread Tolkien 28 too many times, but I expect my fiction to make me think really hard about things.
Anyway, that's just what this article made me think of.