As Kimberly pressed the button the Sex Machine did it's work, and Kimberly started to feel a draft on her belly as her body started to grow taller fast as it starts to age to a more sexually mature age. Her chest felt restricted as her breasts grew bigger and rounder as her training bra snapped, and her panties and shorts started to rip as her ass expanded. Meanwhile her once brother had been experiencing a similar change, his clothes got tighter as his muscles grew, and his limp dick surged a few inches soft. Not to mention their genetics changing slightly allowing them to lose their family resemblance. Then their environment changed slightly as their clothes disappeared. Then the two started to feel real horny.
Kimberly moaned and felt a sort of emptiness in her pussy as she stuffed a couple of her fingers in with one hand and then rubbed one of her large nipples with another... But it didn't feel like enough. Looking to her once brother John she spotted his long and hard cock and part of her told her to get it, take it, and stuff it inside. The two got on the floor and John got over Kimberly and started to slowly plunge his long rod into her while teasing her nipples. Not being used to so much pleasure only a few seconds had passed before the load was blown, and the Sex Machine's magic started to end. The siblings had started to shrink and turn back into siblings, and their clothes reformed. Kimberly going back to her seat, and John going back next to Kris.
Their mother came in asking "What was that noise?"
Kris responded "Oh, they just got into a bit of an argument."
"If you say so..." and then John's mother went back to prepare for the actual baking of their dinner. The three breathed in a sigh of relief as they looked at the Sex Machine on a table in front of them.
Kris said "That was pretty hot you know?"
Kimberly flustered responded with "You're not doing that with me."
John commented "Sure it felt amazing, but that must've been crazily immoral."
Kris exclaimed "But everything turned to normal. This should be fine!" Kimberly and John then saw Kris going for the Sex Machine and didn't trust him with it while he had that grin on his face. The three scrambled for the remote and then-