#are the marines just going along with it to have a handy scapegoat?

[spaztastic-headcannons]

How do they prove it???

Hey so between travel and hubby being sick I haven't had a lot of motivation but this thought came to me last night and had to share--

So outside of Garp spilling the beans to the Marines about Ace and his origins, how do they know he's a descendent of Gol D. Roger? Like Sengoku had the specifics about Rogue holding him for 20 months, which again, only Garp would know except he told Ace (who technically told Whitebeard but I don't think those details came up).

And with his parents dead for well over 20 years, did they do a genetic test to prove it? Could they? Like how can they be so sure??

I mean the masses will believe Sengoku because he states it confidently and Ace's reaction doesn't exactly deny it. And the population that watches the denden feed wouldn't have any reason to question it.

but why would Garp suddenly decide to tell them? unless he confided in Sengoku much earlier and the old goat turned a blind eye hoping that yeah, maybe the kid will become a marine. No reason to bring up bad blood then! (except this is Garp, patriarch to a full contingent of criminals basically molded and made specifically to fight marines and the world government. oops!)

So how do they know? And if ever there was doubt cast on the whole thing, how would they prove it?