User blog comment:Dany1459/Monkey D. Dragon and Gol D. Roger are brothers/@comment-24769684-20161128164641/@comment-24769684-20161128191812

In the last SBS question in the second, Oda says that Garp is 78 and and Roger would be 77 if he was still alive.

Also Oda draws a lot of characters similarly, especially back at the beginning of the series.