The Thomas family was a typical suburban family. Bob was a forty-two-year-old executive with a small telecommunication company and a gym freak. His forty-year-old wife, Mary, could still qualify as a playboy model.

Their seventeen-year-old son, Jack, was a senior in high school and captain of the football team. Although he was fine among other guys, he lacked confidence around girls and never had a girlfriend. He often masturbated to thoughts of his mother.

Their daughter, Tiffany, was fourteen and blossomed early to rival her mother’s beauty and figure. From the age of six, she was in both ballet and gymnastics classes, making her agile and flexible. She was also a bit of a sex maniac, masturbating several times a day thinking about sex with her sexy brother.

Of course, Jack knew nothing about Tiffany’s sexual thoughts about him. They got along like most teenage siblings, sometimes arguing, other times confiding in each other. Their bedrooms were next to each other, so it was obvious to the other teen when one or the other masturbated and came. The actions of one teen commonly resulted in the other teen getting horny and masturbating.

Just before Jack graduated from high school, their parents announced that they were taking a two-week cruise in July and that Jack would be in charge at the house. Jack complained that it would interfere with his partying before going to college, but the parents insisted he take care of his younger sister. Tiffany also complained, stating she was old enough to take care of herself. Mary knew what kind of trouble a teenage girl could get into; she had been there herself and had an abortion at the tender age of fifteen.

“Tiffany, there’s no way you’ll be left unsupervised!” Mary exclaimed.

Tiffany knew better than to continue when she recognized the tone of voice her mother used and didn’t respond.

July came, and the parents went on their cruise. One of Jack’s responsibilities was transporting Tiffany to and from her ballet and gymnastics classes. On the second day that their parents were gone, he drove her to her gymnastics class. She wore a bodysuit that hid very little.

As he drove, he thought, “She looks more like Mom every day.”

Tiffany went inside to her class while Jack waited in the car. The more he thought, the harder he got until he pulled his cock out and masturbated, cumming into a rag.

When she got into the car after class, she said, “It smells like sex in here. Did you jack-off while I was in class?”

“Yeah Tiff, I did,” he replied.

“Who were you thinking about?” she asked.

“That’s none of your business,” he stated, embarrassed about thinking of her while masturbating.

They drove home in silence. By the time they arrived, Tiffany’s muscles had tightened up, and she complained about it.

“Jack, my thigh muscles are getting tight. Would you massage them before I get in a hot bath?”

“Sure Tiffany, lay down on the floor and I’ll loosen them up,” he replied.

She did as he suggested, then he straddled her left leg and massaged her inner thigh. When the muscles relaxed, he did the same to her right leg. He was about to get up when he noticed the crotch of her bodysuit was wet. Because of his inexperience with females, he didn’t know if it was from her class or he caused it.

Meanwhile, Tiffany thought, “He’s got me so hot I’ll have to get off in the bath.”

“Okay Tiffany, go take your bath,” Jack said as he reached for her hand to help her up.

She got up, and without thinking, started removing her bodysuit on the way to the bathroom, exposing her C-cup tits to her brother.

Jack was rock-hard from massaging Tiffany’s thighs, and seeing her tits caused him to explode in his pants. He went to his room to clean up and removed his pants and boxers. Grabbing some tissues, Jack cleaned his groin then put his soiled clothes in his hamper. He then slipped on a pair of gym shorts, going commando.

Meanwhile, Tiffany rubbed her clit and pinched her nipples in the bathtub, quickly having an orgasm. She then further massaged her sore thighs, bringing her another orgasm as the back of her hands rubbed her pussy lips. Now exhausted, she stood, drained the tub, and rinsed under the shower. After drying her body, she called out.

“Jack, I forgot my clean clothes before I got in the bath. Please get me something to put on.”

“Tiff, just wrap a towel around you and get them yourself,” he responded, unsure about cumming in his clothes again.

She did as Jack suggested and put on a pair of loose shorts and a t-shirt. When she entered the den, Jack was already there watching a movie.

“What movie is that?” she asked.

“I don’t know, I just turned it on. It looks like a romantic comedy,” Jack replied.

“Oh good, at least it’s not an action flick. I’ll make some popcorn,” Tiffany stated, then went to the kitchen.

While she was gone, he thought, “I don’t know what she uses in the bath, but I love that fragrance.”

A few minutes later, Tiffany returned to the den carrying a bowl of popcorn and two soda cans. She handed Jack one can, sat down next to Jack on the couch, and placed the popcorn bowl in between them. As they watched the movie, they’d each occasionally reach into the bowl to retrieve some popcorn. As the movie neared the end, they both reached into the bowl simultaneously, and their fingers touched.

A spark seemed to jump from Tiffany to her brother. She reached over, her hands on either side of his head, and kissed his lips. Jack froze, having never been kissed before except by his Mom.

When he failed to react, Tiffany said, “Relax Jack, I know you don’t have any experience but I’ll teach you.”

“But Tiff, you’re only fourteen!” he exclaimed.

“Yes Jack, I’m fourteen. I’m also becoming a woman and know what I like to feel. You’re about to leave for college and don’t know anything about how to make a woman feel good. Let me teach you.” she implored.

“But Tiff...”

“No Buts, Jack,” she interrupted, “lets just be honest with each other about our feelings.”

“Okay Tiff, let’s be honest. Every time I hear you masturbating, I wonder who you’re thinking about. Tell me!”

“You big lug, it’s you that I imagine making love to,” she admitted, blushing.

“Why me? There are plenty of guys your age who’d love to get in your pants,” he asked.

“Because you’re my big brother and girls always idolize their big brothers. Also, because you’re defenseless when it comes to women; you have no idea how they think. Now, tell me who you think about when you jack off!” Tiffany insisted.

Jack turned beet red then said, “Until today, it was Mom.”

“You jacked off thinking about Mom? That’s sick, although I’ve read that it’s fairly common. Did you meet someone new to think about?” she asked.

“No, Tiffany. I’ve known her my entire life,” he admitted without saying it was her.

“You jacked off in the car thinking about me?” she inquired, knowing his answer.

“Yes Tiff, I did. That body suit you wore drove me crazy. When we got home, massaging your thighs got me going again and when you dropped the top of it going down the hall, I came in my pants,” he admitted.

“Thank you for being honest with me, Jack. Now that our embarrassment is out of the way, we can teach each other what we like,” Tiffany stated.

“You’re not mad about me jacking off while thinking about you?” he asked, amazed.

“Of course not, silly. I consider it quite a complement that you replaced Mom with me in your sexy thoughts,” she explained.

“I don’t understand women at all,” Jack said, exasperated.