Commission by jurassicstrain!
We share a common issue with a recent tidbit of news from Nintendo, and Miyamoto himself, stating that the Koopa Kids - most popular from Mario 3, the cartoons, and the more recent New Super Mario series - are actually not Bowser's kids at all. [link]
It's a niggling point because it comes out years after it's been more than popularly established, takes away a significant aspect from the characters, doesn't substitute anything in its place, and, to top it off, Miyamoto doesn't care about story, so him pointing this out means nothing to him, and yet so much to the fans of the characters. Worst case scenario, it's simply to prop up Bowser Jr. over the Koopalings, who, while he has his moments, is still pretty much the Scrappy Doo of all Mario characters (or if you like Scrappy, more like the Poochie of Simpsons).
So this picture is pretty much a fanwanking of the situation. Even if the Koopalings aren't Bowser's biological kids, they might as well be - the perfect, little psychotic bunch of crazies for the King of the Koopas.
But it's all a moot point anyway because we all know how the Koopa Kids came about fo' rizzle. [link]