Because baby making is part of the practice

What if the family didn't worry about birth control while I was practicing with them because babymaking is part of the practice?

Max knew it was a little weird, but he couldn't help but get turned on by the idea of knocking up his family. There was something primal, almost elemental, in the idea of spreading his seed around and having it find fertile ground in whoever he fucked. Still, he knew it could have some consequences without a few tweaks.

What if any babies I make with my family were totally healthy and normal?

There, that should at least ensure that there wasn't any genetic damage from the inbreeding. Max smiled a little, his cock hardening at the thought of how his family would look with big bellies and swollen tits. Putting the machine away again he headed back downstairs. Things were much the same as how he left them. Mom and his aunt were talking quietly, acting as if his mom hadn't just popped his cherry. Lacey had finished eating and he didn't see her, but Stacey was there, and it Max figured it was a good time for practice.

"Hey Stace," he greeted as he came up behind her. "You got plans soon?"

"I was going to meet Fran and Betty at the mall," she told him turning around. "Why?"

"Well I was hoping to get some practice in with you," he answered.

"Seriously? Ugh, fine, we have a little bit before they show. Do you want to go upstairs?"

"Here's good," Max said undoing his pants and gesturing for her to stand up and lean against the table. His cock was rock hard as he peeled her tight jeans off her hips and slid them to the floor.

"Don't forget some foreplay," his mom commented from where she stood watching her two children prepare to fuck. "Kiss your sister a little and maybe play with her tits. They're small but they should be sensitive. Remember, she's a woman, not a Fleshlight. You have to do things to make it feel good for both of you."

Max nodded and began to follow his mom's advice, kissing his sister full on the mouth. His tongue slid inside her mouth without resistance and the two made out for a few minutes, Max founding his sister's smallish tits. They were around a B-cup if he remembered correctly. Hardly small but compared to some of his family she was on the small side.

"You good," he asked his sister his breath panting from their make-out session.

"Yeah, it's fine," Stacey told him also somewhat out of breath. Nodding Max lined up his cock to her pussy, taking a moment to find the right spot before he started to push in. Remembering his mom's lesson from earlier he didn't start thrusting away as fast as he could, but slowly moved in, enjoying the tight grip her pussy had on his cock.

"Wow Stacey," he told her as he started to bottom out. "You're way tighter than Mom."

"Thanks," she said in a deadpan voice, a small grunt escaping her as he bumped against the back of her pussy.

Max smiled and kissed the back of her neck as he started to speed up his motions. Each thrust-in was met with a hiss from Stacey and each pull-out was followed by a moan. Hiss moan, hiss moan. It went on for several minutes. He was happy to simply relax, enjoy her pussy, and listen to the sounds she made.

"You should play with her clit," his aunt spoke up for the first time. "Don't be selfish back there. Stacey, how do you like it?"

"Just ~ugh~ rub it," she told him bringing one hand from her hips down to where her bush met the top of her pussy. Her fingers placed his on her clit and with a few pushes and pulls got Max to rub in a consistent way. It took only a few rubs to get her pussy to suddenly feel a lot wetter and he could feel a tight squeeze as he pushed in.

Almost like a bolt of lightning, he realized he was about to cum, his balls pulled up tight and he pushed as deep as he could go before letting out a torrent of cum.

"~oof~," Stacey groaned as his final thrust pushed her hard against the table. "warn a girl."

"Sorry," Max apologized as he slowly savored his orgasm.

"Yeah, whatever," she ran a hand across her brow as she shot a look over to the adults in the room. "Still not sold on this 'babymaking' part of the practice."

"This is good for Max," his mom told her with a smile at both of them. "It will teach him how it feels to knock a woman up, and give him a chance to try it out on us before he is ready to settle down and become a father for real. Plus it will teach you girls a thing or two about kids."

"It's going to be real rough to do gymnastics with a baby bump."

"If you think that's rough," his aunt told her with a smirk. "Just wait nine months when you're laying back with your knees up squeezing something the size of a pumpkin out of your vagina. That's rough."

Stacey let out a groan at the thought running a hand through her hair as Max pulled out. She pulled her pants up but as she did Max got a devilish idea.

"Hey Stacey, I was wondering if you could help a little more, I need to practice having a woman clean my cock off with her mouth after we have sex."

Stacey didn't respond verbally, simply shooting a glance to their mom, which was met with a smile and nod, before she rolled her eyes and knelt on the floor wrapping her mouth around his junk and licking it clean. Max sighed in pleasure. This had been a real informative morning.