Are Sora and riku brothers

(SOmeone answered this already before and their answer is awesome and i hope that it will be true here it is) we don't know about Riku's parents, but Kairi was adopted by the the mayor of Destiny Islands when Radiant Garden (now Hollow Bastion) was nearly destroyed by darkness and all the people living there were scattered across the many worlds. Kairi washed up on the shore of Destiny Islands during a meteor shower where Sora found her. Kairi was with her grandmother before Destiny Islands so we don't know about her blood parents. But hey So she has a non blood dad at least. But we dont know if her parents or grandmother are alive or dead or whatever. but Sora does at the very least have a mother. when the island was destroyed in the start the mother went with it. but they never say she was turned into a heartless though we assume her heart was never turned. so her"light" was kept alive for when the island came back at the end.

The answer above has a well made hypothisis but being a Kingdom Hearts Original Designer i know the true answer. If you pay close attention in KH1 when you fight the Darkside for the first time Sora mutters the word ''mother.'' It is not shown on the subtiles but if you pay close attention you will see and hear him say it. His mother was definitly turned into a heartless an so far as far as we are concerned his father is still alive; we are thinking of making his father a keyblade lone warrior who left him at early birth through ''The Door'' and he happens to be Riku's father too making Sora and Riku blood brothers. Like i said, its just an idea we havent made a decision yet. Riku's mother and Kairi's parents are still alive and were just stuck in a coma like stage and woke up with everything back to normal. So there you have it, there's your answer! C;
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1.) that's to much speculation

2.) don't delete someones answer just tag your own on after it like this (mine was good)
also this guy isn't a designer he would have said kairi's parents are on another island he's a fake (but me a totally different person then these 2 changed that fact) (i changed the one about kairi)