What happened to the koopalings? Where did they come from, and where did they go? That's what I'm determined to find out. First, as all detective work goes, to find out what we don't know, we must review what we do know: The koopalings are Bowser's children. They first appeared in Super Mario Bros. 3, and made their second and final appearance in Super Mario World. (I will not include Yoshi's Safari, it being a pathetic last ditch effort by Nintendo to raise super scope sales). In these games the koopalings seem to be in the age range of 7 to13. This said, it seems plausible that they were born in the time of Super Mario Bros. 2, as there is no proof that SMB3 was not held a long time after these events. As for their mother, whom there is much debate about, was probably a highly privileged and female Koopa, most likely considered extremely beautiful, who was most likely lost in an accident shortly after Larry's birth.
Now for the big one: the disappearance. It is most probable that they were gravely injured in the events of SMW, and Bowser retired them from the art of villainy, for their own health. However, they may be in secret training, waiting to use their new tricks in the next new attack on the Mushroom Kingdom. That concludes my idea of the mysterious Koopalings.