In the Mario Bros. cartoons, Luigi was always Mario's younger brother. But in Yoshi's Island...I don't remember the story about the stork carrying twins. I must've skipped the introduction the last time I played the game (that was aver 5 years ago!)... Maybe Nintendo goofed with the Yoshi's Island story; because the game Yoshi's Island made the Mario saga even more confusing!
------------------------------
"Bwa ha ha! Guess who it is, loyal Mario fans...
It is I, King Bowser... ruler of all Koopas, big and small. I have come to take over the Mushroom Kingdom (no, not the place...I mean the WEB SITE!)! Deezer, you will surrender your troops to me, or else you will never see your precious Mario again! Bwa ha ha ha ha ha ha ha ha ha!"