The koopalings are NOT related to Bowser!!!
Shigeru Miyamoto confirms that the koopalings are not Bowser's offspring!
During an interview with Game Informer, Shigeru Miyamoto was asked several "burning" questions about the Super Mario lore. Questions like "Is Mario and Luigi's last name really Mario?" (the answer's no) and "Does Mario dye his hair brown?" (the answer is again...no). But one Q&A got my attention; Game Informer asked "In Super Mario Bros. 3, the Koopalings were suppose to be Bowser's children. But there's also Bowser Jr. Are they all his kids, and are they all from different mothers? Is Bowser Jr. a Koopaling?" To which Shigeru Miyamoto responded,
"Our current story is that the seven Koopalings are not Bowser's children. Bower's only child is Bowser Jr. and we don't know who the the mother is."
Wait. WHAT?! Then who are the Koopalings?! Are they related to Bower in another way? Were they adopted? ARE THEY ACTUALLY CLONES OF BOWSER CREATED BY THE UNNATURAL COMBINATION OF SCIENCE AND DARK MAGIC?! What do you guys think the new story is on the Koopalings?