My theory:
(WARNING: FAR FETCHED ALERT) Compromising between the two popular theories, Maybe Mario & Luigi's father was human and their mother was a toad who lived in Brooklyn. When she thought they were old-enough to fend for themselves (right after Mario's rescue in Donkey Kong), She told them the truth about where their history. She told them where to find the far away string of Islands in the Pacific that make up the Mushroom Universe. And My theory about Peach and the reigning monarch, Peach and the Royal Bloodline are the descendants of the first Humans to set foot in the Mushroom Kingdom, and because of their size above the other Creatures, the Toads thought they must be Great Leaders and almost god-like. The Koopa family , such as Bowser and his troopers, however, dind't like the concept of some group of people who were new to the islands take over, so thats why Bowser hates Peach. With Wario& Waluigi, my theory is that their Mother was Mario & Luigi's Mother's sister, making them Cousins, But both of them went to Brooklyn, married, and their husbands opened a plumbing business. But Wario & Waluigi's mother got angry that Her sister's husband was more talented and she tried to kill Mario and Luigi's father (After Yoshi's Island of course) and succeeded when her sister and her husband found out, he divorced her, and she said she never wanted to see her again. So The Wicked Brothers' mother took Wario and Waluigi back to the Mushroom Kingdom, where she told them that Mario and Luigi's dad killed their father, causing them to hate their cousins and causing Wario to want to steal enough money to find Mario & Luigi, travel to wherever they were, and kill them. But after he met the Brothers, they told what had actually happened and Wario and Waluigi believed it, but still dislike their cousins because of their success and popularity, which they envy.
I have a lot more to say, but to be nice to you, I won't.
