In the long interim between Return of the Jedi and Attack of the Clones, I saw a lot of claims that Luke's uncle Owen was actual Ben Kenobi's brother.
I figured from the first time I hear this that the idea arose from somebody misinterpreting an ambiguous pronoun reference (as in: it was written down somewhere—amidst mentions of Obi-Wan and Anakin—that Owen was "his" brother, and somebody inferred the wrong referent). It seemed obviously incorrect to me, given Obi-Wan's attitude toward Owen Lars, but some other Star Wars fans I talked to insisted on it—at least up until the issue was conclusively cleared up in Episode II.
But where exactly did this misapprehension get started? Specifically, is there an identifiable source (such as the novelization of one of the original films) that was misinterpreted? And where did the erroneous claim first appear in extended universe materials?