User blog comment:Dany1459/Monkey D. Dragon and Gol D. Roger are brothers/@comment-24769684-20161128164641/@comment-4410366-20161128190649

I initialy wrote half brothers, but since english is not my mother tongue, i changed it. I indeed meant half brothers.

I must say that the link you provided didn't clarify things for me (i only watch the anime, and that  which you said is not shown). Even if it's true, the possibility of these families being related is still strong.