Definitely all speculation for me. I didn't know that only F1 lessers could be used. I thought it was just any lesser mixed with a sibling that carried the hidden platty gene. I guess it wouldn't HAVE to be an F1, but I'm guessing that you cut your odds in half every generation if the lessers from a platty also have something special. I wondered why I hadn't heard about mojos or butters being bred to F1 siblings. Oh well.