Okay, who sniffed the glue?

I browsed through a book called Harry Potter Slueths at Hastings today. Imagine my surprise when I discovered they were absolutely positve James Potter and Remeus Lupin used a switching spell on themselves shortly before 'James' died. Thus Lupin is really Harry's father. They cited numerous places in the books where apparently J.K. Rowling hinted at this. As for myself, I think they're a little off the rocker.