A Lesson in Biology
Copyright© 2026 by Lubrican
Chapter 1
Coming of Age Sex Story: Chapter 1 - She wanted to be a cheerleader but her grades were too low. Summer school might solve that problem. But she needed a tutor to make sure. Her mom got a name from the school and he was hired. When they got to the biology tutoring, she wanted to understand the reproductive system. He was happy to teach her about it.
Caution: This Coming of Age Sex Story contains strong sexual content, including mt/ft mt/Fa Mult Teenagers Consensual Heterosexual Fiction Incest Mother Son Brother Sister Harem Interracial Black Male White Female First Lactation Masturbation Oral Sex Petting Pregnancy Voyeurism
Robin was both excited and bummed. Her dream of becoming a cheerleader was within reach ... but she couldn’t touch it, yet. Her grades weren’t high enough. It wasn’t just that she wanted to be one of the cool kids. Her mother had been a cheerleader at Ole Miss and then Miss Mississippi in the Miss America contest. Robin wanted to be just like her. She was built perfectly. A tape that went around her back and under her breasts read 36 inches. It read 24 around her waist and 35 around her hips. She got her bras with a C cup that fit her breasts perfectly. She had long, blond hair and weighed around 110. So she was physically perfect for the role. But her grades in three classes were a D. Her mother told her to retake those subjects in summer school. Her dad, who got paid very well, said to get a tutor to lead her through the courses, since she would have to cram a whole semester of work into just two months.
Her dad was almost always gone for his work, which involved some kind of inspections across four states. So her mother went to the school and asked where she might find a tutor for her daughter.
Two names came up. One was Nancy Yeager, and the other was Marcus Wilmington. It turned out Nancy’s family was going on a long vacation and Nancy was going with them. Marcus, it turned out, was available and eager to take the job because his mother had to work two jobs to support him and his two sisters.
Mrs. Fitts noticed that Marcus was black. It would have been impossible for her not to. She was born and raised a southern girl and familiar with the way young, black men behaved in school. She had never dated a black boy. Her parents would have been scandalized, then had strokes, and then further scandalized. So, while having been exposed to black people, or at least black high school students, she had never actually had a conversation with a black person in her life. What made this more interesting was that Marcus didn’t fit the usual profile of most black young men in school. He wasn’t a jock, though he looked like one and worked out with them in the gym. He wasn’t in a gang, but the bangers liked him because he helped them with their grades. There were twenty-two black students in the school and only six of them were girls. Marcus wasn’t known to date any of them, or any white girls either. He was a geek. Other geeks liked him and people who needed his intelligence liked him but he kind of cruised below the radar. He was a genius, and that’s what Robin needed.
Marcus suggested and Robin liked the idea of taking the classes online in addition to the classroom lessons. He spent three hours with her each session and, after a full month of his help, the tests provided by the online school didn’t look forbidding at all. After the first one, on which she got a C, all her test scores were either A’s or high B’s and she liked not feeling stupid. She actually looked forward to the quizzes. She also liked it that her tutoring took place in her bedroom, for the most part. There were some field trips in the biology class, to collect leaves and insects. They also went to the zoo, where Robin paid attention to the differences in animals for the first time. Before this a tiger was a tiger and an elephant was an elephant. Once she paid attention, the six different sub species of tigers and two of elephants were fascinating to her.
It was mid-summer and the first cheer practice would be in less than a month, as in two weeks. She was not nervous about taking her final tests in her summer courses. She was sure she’d do well because Marcus had a knack for helping her understand what she was learning and why it was important. One that was done, remembering it was easy.
One evening she forgot that it was a “Marcus day” and went for a long run. When she got home she was sweaty, so she took a shower. In her mind there was nothing planned for the rest of the day so she put on her “jammies,” which consisted of a pair of tight “boy shorts” and an old T shirt she had stolen from her father because she loved it so much. When she first filched the shirt it was ridiculously large on her ten-year-old frame. Six years later it was still loose on her, but she now filled it out nicely.
She thought she’d lie down – just for a minute – and was sound asleep when the doorbell woke her up. She lived in what most people in town called “The Fitts Mansion” and the doorbell practically played a song that lasted a good five seconds. The bell sounded again and she sat up. She looked at the clock on her bedside stand and was confused when it said 6:13 when it should have only said 4:13. She realized she had fallen asleep when the bell sounded the third time. She realized it was probably Marcus, who came every other day, usually around this time. He almost never stayed past nine P.M.
Without thinking about her attire, she ran to open the door. When she opened the door it was Marcus. After he stepped inside he said, “You win.”
“I win what?” she asked.
He pointed at her bare toes and then ran his finger up to her tousled hair. Then he indicated himself, pointing at his faded, mustard-colored athletic shorts and a tank top which revealed shoulders packed with muscles. His teeth, exposed as he grinned, looked almost blindingly white when he smiled, because his skin was so dark.
“You’re better looking than I am,” he said.
Robin giggled. She had spent enough time with Marcus that she thought of him as a friend, now. Their relationship was relaxed and, because of that, she did not consider her jammies to be improper attire.
“Why are you so sweaty?” she asked, wrinkling her nose.
“I was playing basketball with Tasha and Keesha, them against me. I used to beat them routinely, but they’ve grown up a bit and now I have to work at it.” Tasha and Keesha were his sisters. “So why did I have to ring the bell three times before you opened the door?” he said. “I was beginning to think you weren’t here.”
“I’m sorry, Marcus,” she replied. “I ran an extra mile today and was tired. When I lay down I fell asleep. It turned into a nap I didn’t intend to take.” She frowned. “You’re the genius, here, so explain to me why we say we ‘take’ a nap? Where do we take it from?”
“Nap is a noun, which must be acted on to reveal something,” he said. “We have twenty-four hours in a day and if you take one of those hours for the purpose of napping, you only have twenty-three hours left in your day. You take the time and use it. It’s the same thing if you take a break or ‘take five.’ What is confusing to some people is that if you nap, then suddenly the word is a verb.”
“You know everything, don’t you?” she said. She smiled.
Marcus looked Robin up and down and admired her big, unfettered breasts and so much leg that he wondered if she was wearing anything under the shirt at all.
When she saw his eyes raking over her body she realized what she was wearing.
“Marcus! I am astounded. You don’t usually look at me like that. It actually comforts me that you can act just like a normal guy.”
“I am a normal guy,” he said. “You just haven’t caught me looking before.”
“So you’ve ogled me before?”
“Come on. You know you’re hot. So’s your mom. What I like about both of you is that you don’t use that asset in a snooty way.”
“Well, whatever. I should change into something more appropriate.”
“Please don’t!” Marcus said, “I don’t get to ogle hot white girls very often. I promise I’m harmless.”
“I know you’re harmless. I’ve gotten to know you pretty well. In fact, I’d have to say I know you better than any other male. I think I know you better than I know my daddy.”
“You’ve lived with him sixteen years,” said Marcus. “Weren’t you paying attention?”
“He spends three weeks of each month traveling. When he’s home he does his hobbies and stuff. I talk to him at meals, but that’s about it.”
“That’s sad. You have a father you only talk to a little bit and my father is never around to talk to.” She already knew his father had abandoned his wife and children, leaving Delores to raise three kids alone.
“It’s okay. I’m used to it,” she said. “Come on in. Are you sure that if I wear this it won’t distract you?”
“It’s your mind that matters and I’m here to help you with school, not your clothes.”
“In this case there’s aren’t many clothes to help me with,” she said, with a crooked smile. She was used to boys ogling her. Usually she just ignored them but for some reason she felt a little shiver as Marcus, who was six inches taller than her and coal black, checked her out. She felt her nipples crinkle and didn’t have to look to know they were stiff and poking through the shirt. But Marcus was a geek and a pal, she thought. And he never dated, so what could happen? “Do you promise to behave yourself?” she asked, more out of social necessity rather than any real concern.
“Don’t I always behave myself?” he replied.
“Okay then, let’s get started,” she said, “My mom is at some volunteer thing and the note she wrote me said she won’t be home until ten. So we have a few hours to study.”
“Okay, what do you want to start with tonight?”
“Well, we can start with English, then math, and do the Biology last. My room is a mess, but I know you’ll cut me some slack, right?”
“Your room looks nice even if it’s a mess,” he said. “Some day I’ll show you my room, which is four wall-papered walls, a mattress on an iron bed frame, and a desk missing one leg that I have boxes stacked under. I store my clothes in plastic bins because when my dad left and we had to move, we couldn’t afford to bring all our furniture. Trust me, your room could never look bad to me.”
“I’m sorry you’re in that situation,” said Robin, reaching to touch his arm.
“It’s not your fault,” he said. “I’m used to it like you’re used to the relationship you have with your father. And the money your mom is paying me to help you is really helping us, so you’re actually helping me while I help you.”
Robin’s father got paid a lot. He had bought the mansion when she was two and it was already paid off. Her mom paid the bills and the two of them usually ate together or watched a movie together and such. There was a strong bond between Robin and Molly, her mother, and they lived a very comfortable life. Because of that, Robin had never been exposed to poverty and didn’t understand it. Marcus said his mother worked two jobs, so shouldn’t that be enough for him to at least have decent furniture? Marcus was exposing her to much more than “book learning.”
Another thing that affected her was that Marcus was the first black boy she had ever talked to. She had expected him to be different, but as time passed she decided he was just like any other boy, only with black skin and different hair. And, in her mind, there was so much social distance between them that there could be no relationship that involved intimacy. She liked him. In fact she liked him a lot, but he was black and she was white. She was rich and he was poor. She was stupid, in her own mind, and he was a genius. There were so many differences that she just assumed nothing could happen between them other than what they were currently doing.
As an hour went by Marcus enjoyed the view. He loved looking at Robin as she read an essay from her English book. Robin sat on her bed with one leg bent under her and the other stretched out in front of her. As she moved around Marcus got a very quick shot of the boy shorts she was wearing. They clung to her body, revealing only her thighs, but the bottom of those shorts was only four inches away from what made her a female.
Marcus had appreciated Robin’s appearance many times. He was as normal as grass is green, in terms of being a male. The difference was that his libido wasn’t as restricted or frustrated as most other boys. That was a secret he had to make sure Robin never found out.
He had gotten erections around her before, too, but he usually wore jeans, which could control his black snake and hide it from this cute white girl. Coming straight from the sibling basketball game, he was wearing loose shorts, today, something that would lead to a whole new facet of their relationship.
‘Damn,’ Marcus thought to himself, ‘It would be nice if she didn’t have such beautiful, long, distracting, pale legs.’
He suddenly realized that if he got a boner in these shorts, there was no way he could hide it. He was feeling dual but opposite urges. The idea of her seeing his stiffy made him get even harder, while he tried, in vain, to reposition himself on the bed. He tried sitting and lying down, and even thought about excusing himself to go to the bathroom, where he could beat off. He knew he was three quarters hard, which meant he could make it lie down on any part of his groin, but his shorts were too short to contain it. If he pulled it up, it would show where it protruded from his waistband. If he moved it horizontally, it would fall to where his leg emerged from his shorts, and expose itself there. He cursed himself for not thinking about this. He tried lying on his side with his cock resting on the gusset of his shorts. It still made a huge bulging line, but maybe she wouldn’t see it.
She closed her Math book.
“You ready to do Biology?” he asked.
“Yes.”
“Then let’s get it done,” he said. He hoped it would go quickly so he could go home and get rid of his boner. If nobody was home and he masturbated, it would be like he had fantasized before. He would think about Robin while he stroked one out.
Robin tossed her math book on the bed and Marcus grabbed it so he could lay it against his shorts and hide his bulge. His cock was almost hard, but the fear of disgusting or scaring her and being branded a pervert kept him from getting a full hardon.
“Where are we?” he asked.
Robin opened the textbook and began letting pages slip past her thumb.
“Chapter twelve. We finished chapter eleven last time you were here, remember?”
“Oh yes,” he said. “Muscles and tendons.”
“Yes.”
“So what is chapter twelve?”
She flipped three more pages and stopped with the book open, looked down and read something, and then blushed, which Marcus thought was odd. He had never seen her blush before.
Then she turned the book and showed him what was on the page.
“The human reproductive system,” she said as her face got even pinker.
Marcus thought about what her math book was covering and the irony of it made him laugh.
“What’s so funny?” asked the cute teen.
“Nothing,” said Marcus as he felt his boner throb. “I just figured you already know everything about the reproductive system.”
“Why did you say that?” she asked. He saw genuine confusion in her eyes.
He wasn’t going to play games. When a girl looked like her, it suggested she’d had sex dozens of times.
He turned to the page of an animated view of the male penis and asked her, “How many of these have you seen before?”
She blushed and said, “None,” she said. “I don’t let boys get that far on dates. I might have seen my dad’s. He walks around naked sometimes when he’s home, but I never tried to see his ... I mean, ewww.”
“I’m sorry,” he said. He actually felt bad that he had assumed she was ... experienced. He realized he was stereotyping her.
“So ... help me understand girls. Do girls ever think about seeing one? Have you ever wanted to see one?”
She blushed beet red.
“I’m supposed to say no,” she said.
“Don’t worry about what you think you should say. We’re studying and you should say whatever you need to, to get questions answered.”
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