Marco is one of the remaining Whitebeard pirates, just like the others, Marco considers his captain Edward Newgate to be his father

Marco's eyes looked at a small book in his late captain's pocket which was the clothes his captain was wearing on his captain's grave

Marco took the book and read it, and to his surprise it turned out that his captain had a biological daughter but she was not giant like his captain

Marco: "Adriana, Oyaji's daughter? And Oyaji wants me to marry her?"