Gunko is either
1) A Nerona and Oda is hiding it for later hence why she's the only one with no family name reveal so far. That'd make a Imu descendant
2) The Luffy to Shamrock's Shanks. A kid he saved and who idolize him. It would contrast the influence of the twin brothers on the next generation. Problem is Shamrock doesn't seem so nice that he would raise a random kid to CD and HK statut.
3) A regular ass CD and Oda just brain farted and forgot to give her family name during her intro
1) A Nerona and Oda is hiding it for later hence why she's the only one with no family name reveal so far. That'd make a Imu descendant
2) The Luffy to Shamrock's Shanks. A kid he saved and who idolize him. It would contrast the influence of the twin brothers on the next generation. Problem is Shamrock doesn't seem so nice that he would raise a random kid to CD and HK statut.
3) A regular ass CD and Oda just brain farted and forgot to give her family name during her intro