Jeff got done with his shower and went back to his room, a towel wrapped around his waist. He saw his sister Rosie was now watching one of her Strawberry Shortcake tapes in the living room, not even looking up as he walked through. At the Chronivac, Jeff decided to play around a bit. Rosie's settings were still up, so he clicked a few things at random. He increased breast size to c-cup, just for a giggle, and watched the chest measurement increase to 24". Curious, he clicked on a Panel that said "package". The package panel showed Jeff all sorts of animal changes, as well as hybrids as he looked through it. He clicked on "cat-girl" pretty much at random (okay, not at random - he thought cat girls were hot). He changed her hair/ fur color to red.
When Jeff dragged his mouse across "gender", a popup window showed up, reading "Virgin/Prepubescent Toggle" and it was set at "On". Without thinking, he switched it to "off" and when the popup closed, he saw he had accidentally clicked "gender" changing the setting to "Male/Female". He looked at it and changed it to female. Jeff noticed a new series of panels, obviously switched on by his changing the virgin toggle since they all related to sex. The "libido" slider setting was average, the "orientation" slider was almost to the end of "hetero", and the "resistance" slider was high. He read the info about them and without thinking, he slammed them all the was to the right, except the Orientation which was already there, which he slid to the middle. The new settings were Maximum Libido, Bisexual, and No Resistance.
Jeff heard a squeal and went out into the living room to investigate. On the floor in front of the TV was his little sister Rosie - but changed. Her perfect round tits were about to bust out of her t-shirt, despite the fact she was still 3'8" and child-sized. She had cat-ears and a tail that was swishing about madly, as well as blood red fur the same color as her hair all over her body. Her shorts and panties were around her ankles, and her hands were busy both buried in her pussy, and they were working like mad. The little cat-girl moaned with the pleasure she was giving herself.
Jeff's cock became hard very quickly at the sight of her and he discarded the towel, he got on his knees and began playing with her tits, large and round, yet small enough to fit into his hand. She gave a moan of enjoyment, her hands busy until she began to huff and puff and moaned loudly as she arched her back. Jeff saw she had cummed and when he saw her pussy. The whole situation started getting too hot for him to think in, so Jeff didn't. Instead, he sat up and pulled his sister's hands away from her mutated genitalia. She looked at him expectantly, as if silently begging for something.
Jeff gasped as his cock entered her pussy. There was no resistance, and the girl mewed in pleasure, her tiny hips surging up, trying to bury him deeper in her. It was the tightest, hottest pussy Jeff had ever fucked. He pumped into her, trying to bury himself entirely into her with each stroke as she clung onto him and mewed her pleasure. "More," she squeaked. "More ... more ..." She moaned in pleasure. Jeff's body entirely covered Rosie as he fucked with mad abandon. Then her pussy began to spasm around his dick, and her cries became shouts, and Jeff knew his sister was cumming. With a groan, he shot his load into her, cumming like never before. He got off her and before he could move she grabbed his cock and started sucking it. She kept it up till Jeff cummed into her mouth. He patted her head as she fell sleep. Glancing at the clock, he noticed that his mom was going to be home soon. Getting up, he went back to the Chronovac and hit the "Save" button (no way was he going to deprive himself of sex like that, even if she was his sister!) and reset her to normal ...
Or tried to. While everything went back to normal, the Virgin toggle refused to budge. And the settings still showed Maximum Libido, Bisexual, and No Resistance. Flipping through the manual, he found out that the "virgin" settings were useless once the subject was no longer a virgin. And the sex-based settings were stuck due to a bug in the software that only showed when the virgin toggle was used and the subject lost their virginity. Jeff pondered this - it probably wasn't too bad. He looked in the living room and Rosie was back to normal size, species, and gender, with sperm coming out of her pussy. He took her to her room and cleaned her up, and she awoke and blew him a kiss.
Back in his room, Jeff experimented on himself, changing gender and species and back again. He also found a "fetish" listing (his own settings had 'furry', 'dominate', and 'incest'). As his mother drove up he scanned her out his window. Calling up his mother's settings, he found, Caucasian, 35, Female, 5'8", breast size 36B, 145lbs, 36" chest, 30" waist, 35" hips, 32" legs. But her sexuality readings were a shocker. She was listed as high libido, bisexual, and low resistance! And the 'fetish' settings listed 'submission' 'humiliation' and 'mild masochism - spanking'! Jeff had had no idea about his mother. And the knowledge made him hard as a rock.