The two sets of Jacobson twins had been home from college for about a week when the summer boredom started to hit. Their mother, Jeanette Jacobson, had decided to leave for the week to visit her sister in Maine along with their younger sister, June and their baby brother, Josh. The four siblings were all sitting down to dinner discussing their plans for the evening.
"Let's go skinny dipping in the pool!" Jillian chimed in, laughing. Jillian and Julia were 21 and had just finished their junior year at UConn. They were identical twins, both with voluptuous rear ends and perky breasts. Jillian had always been more feisty, though, and her personal style reflected that fact. She was currently wearing a low-cut red sundress, her long dark hair falling past her shoulders in large, bouncy ringlets. Julia, on the other hand, sported overall shorts, a summer camp tee-shirt, and long pigtail braids.
"Come on, Jilli, that's no fun, we're all related." Julia sighed, flashing a hint of naughtiness at her twin.
"Well there's nothing better to do," sighed Jason.
"And it's certainly hot enough," finished his fraternal twin Jonathan.
"Well,...we'll turn off all the outside lights, so no one is embarrassed," said Julia.
"Okay, but there's a full moon tonight," teased Jillian.
"Actually it's a waxing gibbous moon," countered Julia. "Dumbass. Tomorrow is the full moon. But hey, let's just do the dishes and get to it. 'Sides, I haven't been skinny dipping since freshman year."
"YOU went skinny dipping?!?!" Jason joked in mock shock. Jason and Jonathan, the fraternal twins, were 19, and had just finished their freshman year. They looked very much alike, both having dark hair like their sisters, but Jonathan was a bit taller and leaner, and Jason was a bit shorter and had more pronounced muscles.
They all helped with the dishes, then went out to the pool. Julia hit all the lights, but as Jillian predicted, it was quite bright outside due to the moon. They all turned their backs to each other and stripped down. Julia left her panties on. Jillian jumped in first, followed quickly by her three siblings. They splashed each other and joked around for several minutes before resorting to peacefully swimming around, casually chatting. It was right about then that the moon caught Julia's upper body just right as she was facing Jonathan. He was dumbstruck at how utterly hot she was. Her pink nipples stuck out from the cold water, her hair gleamed wet in the moonlight and he felt himself start to get hard. He fought down his incestuous thoughts immediately. Baseball. His 65-year-old gym teacher-with-saggy-boobs naked. Okay. He temporarily was able to calm his cock down. What was he thinking? She was his SISTER! He'd always thought Jillian and Julia were gorgeous, but had never had sexual thoughts about either of them before. Julia broke his train of thought.
"Okay you crazy people, I am freaking freezing. I'm getting out." Jonathan watched as she hoisted herself out of the pool at the side. Her wet panties clung to her so that he could see just a faint outline of her clit and inner labia just slightly protruding out from her outer labia. The sight drove him mad. He turned around and quickly dove under the water and swam around until he couldn't hold his breath any longer. Luckily by that time she had already gone inside. Eventually the rest of them went in. That night, Jonathan masturbated to that spectacular image of Julia standing by the pool.
The next morning at breakfast Jason and Jillian were cavorting as always, teasing each other mercilessly. Jonathan stayed unusually quiet, and Julia had her nose buried in a book as usual.
"Why so quiet, Jon?" asked Jason
"Maybe I don't always need to participate in the Jill and Jason freakshow!" He joked.
"Whatever, spoilsport," laughed Jillian, throwing her head back, causing her curls to bounce. Jonathan took in a sharp breath. Goddamn, she was fucking hot, too! He'd done a few girls at college, but none of them were as hot as his own sisters. He tried to bury that thought as well, but it was hard with the two of them right in front of him. He got up quickly and went up to his room.
"What's his problem?" inquired Jillian.
"I'll go check. But I bet it's all your fault!" Julia stuck her tongue out at Jillian. She then proceeded to skip up the stairs and knock on her brother's door.
"Come in" he agonized, but he couldn't just turn her away. She opened the door to find him sitting on his bed with his head in his hands. She shut the door and walked over to sit beside him.
"Hey, " she soothed, placing her hand on his shoulder. "What's up?" He took his hands away from his face. He looked at Julia longingly. She shifted uncomfortably.
"Umm, Jonathan..." before she could say anything he pulled her face to his and kissed her on the lips. Her lips were tight, but he could tell they were as soft as they looked. He pulled away and she looked at him, shocked.
"Uh.....What was that? WHY was that...?"
"You're so beautiful, Jules." He sighed and looked at her.
"Jon, you shouldn't be saying that. I'm your sister, and that's really kind of creepy and weird."
"Sorry. I take it back. Oh fuck. Sorry! I am so out of control, I can't even explain it to you."
"Okay, but." Julia was having a serious dilemma. She had been surprised, but weirdly aroused by Jonathan kissing her. No! He was her little brother!
"But what?"
"Just, nevermind."
"Okay....I'm sorry."
"Let's just forget it happened." She got up and walked back downstairs.
"Jonathan's just being a little emo kid about some girl." She announced.
"Hahaha, Jonathan the Lady-Killer." Laughed Jason.
"Yeah right," responded Jillian.
"Okay you two clowns. I'm going upstairs to finish my book in peace."
"You're such a freakin geek!" Exclaimed Jillian.
"Whatever. At least I'm not stooopid like someone I know."
"Hey, we all know that Jason's a little special. You don't have to make fun of him because he's challenged."
"Hey!" complained Jason.
"I meant you, little miss whore-tastic."
"Me? Never." Jillian grinned. It was a well-known fact in the family that Jilli was a big slut with both genders at school. What was not well known was that earlier in the year the girls had been committing some relatively incestuous acts one night on a dare at a frat party. This particular incident was currently running through Julia's mind. She was trying to rationalize why what they had done then wasn't incest, but kissing her brother was.
Jason went up to Jonathan room and barged in. Jonathan had begun to masturbate, and he jumped at Jason opening the door.
"Umm, could you please knock next time?" Jason grinned and shut the door.
"Nice stiffy, man. If I were a chick I'd be laughing, but since I'm not I feel sorry for you, man."
