User blog comment:Staw-Hat Luffy/Silvers Rayleigh is Luffy's uncle/@comment-1595565-20121028170307

Buggy was with Rayleigh before Luffy was even born. It was a joke, don't look into it too much. Also, if he were Garp's brother, there'd be a D in there somewhere. You're overanalyzing something that was meant to be a joke.