I agree. I'm not sure how the theory even materialized; it is pretty easy to claim something which can't really be proven true or false, I guess. That said, I would be interested in seeing a "study" similar to this one at some point "proving" or "rejecting" the claim.I think what they mean is that breeding with pokemon that didn't come from Kalos (X and Y) affects the odds of hatching a shiny from it. Some were saying that it makes them rarer. I have been breeding with a non-kalos japanese ditto, and have gotten three shinies in about four-five hundred eggs, so I don't believe that it makes a difference if a pokemon came from an older game.