Can you quote that player's guide in greater context? Mario has never been stated to be from Brooklyn from any game or instruction manual as I know of. That might be the only video game related source to say so.
1: After the events of M&L: PiT both Baby Mario and Baby Luigi were sent to Earth. Here they grew, Mario fought Donkey Kong and Foreman Spike, etc. During Mario Bros. the bros. fought a bunch of creatures that used the New York sewer system to get to Earth. The Bros. held off these guys and accidently ended falling down a Warp Pipe that brought them to the Mushroom World.
2: Mario and Luigi never left the Mushroom World. They stayed here and grew up here and all the games which we think happened on Earth happened in the Mushroom World (Donkey Kong, Donkey Kong Jr., Wrecking Crew and Mario Bros.). Mario, instead of fighting Donkey and Spike in New York he fights them in Big Ape City or something as the Donkey Kong Land manual implies (I said imply, not says).
"Travel by zeppelin to Donkey Kong's favorite stomping ground, Big Ape City. The sight of that familiar skyline might bring back fond memories, but don't waste your time sightseeing when there are Kremlings around!".
It could pretty much go either way but the Earth one is kind of complicated by the appearance of several characters supposedly from Earth in the Mushroom Kingdom, Pauline and Spike have both shown up in a game taking place in the Mushroom Universe atleast once.
Like I said, the SM64 player's guide may be the only video game source to say that Mario is from Brooklyn (if it even does [It probably does.]). I don't think Mario Bros. or Donkey Kong has ever been said to take place in Brooklyn by an official source. I think that whole Brooklyn thing was largely a product of the cartoons.
We could probably just stick a, "though this is debated" notice in the part of the Mario article that says he's from Brooklyn. Unless Miyamoto or a manual/guide says Mario is from Brooklyn it will remain a mystery, and we all know how good Miyamoto is with continuity.
It would make sense if they did come from Brooklyn considering 99% of the population of The Mushroom Kingdom are Toads, Koopas, Goombas etc. except for that fact that Princess Peach, Daisy, Wario, Waluigi and others are human. Nintendo really need to clear this up.
I dont like the idea. Marios supposed to be Italian. In the games hes always talked like hes Italian not from Brooklyn! And Ive never seen anywhere on any Mario game that Marios from Brooklyn. Why else do you think hes obsessed with spaghetti and ravioli? Why do you think when he loses on M64 he says "Mamamia"? Well your right about the Mushroom Kingdom thing. I say hes either one of those.
You can be Italian and have an Italian accent and not actually be born in Italy. Besides, some people living in the Mushroom Planet have accents, Dupree is French and those Bob-ombs in Fahr Outpost sound Russian.