His sister remade and a new half sister, playing together.

Josh walked out of his bedroom and was heading for the door when he heard a soft moaning coming from his sister's room. He walked over and, because her door was open, looked in. He almost gasped when he saw a sexy teenaged brunette lying naked on his sister's bed with an equally sexy, equally naked blonde's face between her legs.

It took him a moment to realise that the brunette was his formerly fat, pimply 18 year old sister, Amy, and a few more to recognise the blonde as his half sister, Elena, who hadn't existed before since she was the daughter of one of his father's other wives. He realised that this situation was probably normal in a world were all women were bisexual, sex was considered a normal pastime and men married more than one woman. He also realised that the scene was turning him on and that, far from feeling disturbed by the idea of having sex with his sister, he was totally fine with the idea. In fact it seemed a fairly normal thing to do. There wasn't even the illicit thrill he might have felt about it before. In a world were there was no chance of inbreeding (unless the woman involved chose it) **** seemed as normal as any other type of sex and just another kind of family bonding.

He looked at his sisters, who were both enjoying themselves too much to have noticed him. He wondered if he should leave them to enjoy themselves, make his presence known or even walk in and ask to join them. He certainly needed some kind of outlet for the pressure beginning to grow in his pants.