Quote from blackgamer
its garp's grandson...but wouldn't luffy be more known as dragon's son? i mean, at the war at marineford it was revealed to the whole world and not the relationship between luffy and garp or between garp and dragon.becaus of that, i dont believe that it's worldwide known that garp's grandson is luffy. i don't think the marine goes around telling anyone that garp (the great hero who cornered the pirate king multiple times) has any connection/bloodrelation/relationship with dragon (the most wanted criminal). maybe i've understood something wrong...
Yeah, during the war they said Luffy was a big threat to the future and that he is Dragon's son and Garp's grandson.
It's also very possible that alot of the older pirates that was around during the Gol D Rogers era are more familiar with Garp then they are with Dragon, seeing as how Dragon don't mess that much with pirates and are going after marines instead. I think that the pirates who are most impressed with Luffy being related to Dragon are the younger pirates.