Son Swap

It was three months after our 18th birthdays and a week after graduating high school when our two moms turned our lives upside down. Yes, you heard me, Tim and I have two moms.

At the time we were born, four days apart (me first), our moms and their parents were estranged, after their declaration of being a lesbian couple, and Mama Sarah and Mama Marie made the strange decision to not reveal whose son was whose when they announced that we had been born, in the hope that both pairs of grandparents would treat us equally. They gave us both the hyphenated last name Wolff-Carter, although they hadn't been able to marry yet. The existence of grandchildren did mostly end the estrangement and we were accepted as grandsons by both families.

This secret continued as Tim and I grew old enough to realize that we had each been born to a different mother instead of being twin brothers. So, we took for granted that we had two moms and when people asked, "Which one is your real mom?" we could only answer, "They won't tell us."

When we were 15, they sat us down for a family meeting and finally showed us our birth certificates and the adoption papers that gave them joint custody. These revealed that Tim was Mama Sarah's son and I was Mama Marie's. Neither listed a father's name. When they legally married a month later, I walked Marie down the aisle while Tim did the same for Sarah.

We had grown up loving both of our Mamas and Tim and I reassured them that knowing the truth didn't make a difference to how we loved them.

We never expected that to be tested.

When they called another family meeting like the one when we were 15 on that Friday night in late June, we had no idea what it was about.

Once we were seated, Mama Sarah began, "Hear us out on this, please. What we are about to ask from you will sound really strange, but here goes. Mama Marie and I want more children, since you two are headed to college soon. We decided several years ago that our preference would be for the two of you to father them, but we needed to wait until you were 18 to ask."

"What did you say?" I sputtered, looking over at Tim, who looked as stunned as I felt.

"You heard me, Aaron. You would impregnate me and Tim would do the same for Mama Marie. That way, Marie's baby will be my grandchild and vice versa. Before you say it, 39 is not too old. Also, we should both be ovulating in a couple days."

Mama Marie took over. "You would sign contracts like you were donating sperm and your names would be left off of the birth certificates. We would expect you to keep this a secret, let us raise them and just be their big brothers."

Tim asked, "Couldn't we actually do artificial insemination, like you did to have the two of us?"

Marie said, "While step-parents having sex with adult stepchildren is not a crime, we doubt any fertility clinic would agree to using your sperm."

Sarah continued, "Besides, you can't tell us you've never fantasized about us. We've both noticed you looking at us more and more differently since you learned who your birth moms are and aren't. Especially when you've been without girlfriends and horny, like you are now. Looks you would have avoided giving us you now let linger, while you still turn away from watching your birth mom the same way."

Marie said, "We've seen your Internet histories, too. You both watch plenty of both MILF and incest porn, especially the step-mom/step-son stuff, but some that pretend to be real moms with real sons, too. We also saw searches with 'mom swap' and 'son swap' as keywords, although there don't seem to be that many videos like that, certainly not whole series like there are for daughter swaps, where two dads have sex with each other's daughter. But it shows you're at least turned on by the concept of incest."

"Um... I use incognito mode. How could you know what I watch?" Tim asked, signaling that he wasn't denying it.

I couldn't deny it, either. The incest pornos were the videos that turned me on most. I was watching almost nothing else since Cara had broken up with me right after prom. It felt like a fixation. One I tried (and failed) to deny had anything to do with Mama Sarah directly.

Marie answered, "That mode suppresses the browser's history, it doesn't affect the site logging we left set up on the firewall. We've learned a lot about your viewing preferences. Aaron's watching a lot of blonds like Sarah and your preference is for brunettes like me, Tim. Tell us if we're wrong about that."

Silence from us as we looked from face to face.

Sarah said, "So, we're asking for a son swap, until we get pregnant, if not all summer. We'll give you a day to think about it and talk to each other. If you're not both a yes, we'll go with anonymous donors instead, but we want to both be pregnant before you leave for college, either way."

~~~~~

Tim and I retreated to his bedroom to discuss the bombshell whose fuse had just been lit.

"Can you frigging believe this?" he asked, flopping on his bed, while I sat at his desk chair.

I shook my head no. "I feel like I'm dreaming, to be honest. Not like a nightmare, but it does seem way too good to be real."

"You're leaning towards saying yes, I take it?"

I said, "If it truly stays between the four of us, I can't actually think of a reason to say no. What the rest of the world would think won't matter, because they won't know. I would do anything to make either of our moms happy. Even this. Besides, how many times have our friends called both of them MILFs to our faces and pointed out that one is our mom and the other is just our step-mom? They've practically egged us on to make a move."

Tim nodded. "Instead, our moms made the move first. And have been thinking about it for years, apparently, waiting until we were old enough. I'm... I'm in if you are."

"Yeah. Just in separate rooms, okay? Not like those videos where the dads swap their daughters side by side."

"Afraid to see me in action?" he asked, grinning.

"Not you, Mama Marie. It's enough that I fulfill my fantasies about your mom, I shouldn't be adding fantasies about my own."

"Good point."

~~~~~

"Are you nervous, honey?" Sarah asked, when she came into my room the next night, wearing a light blue satin robe under which I could glimpse lingerie of the same color. I was sitting on my bed in just a pair of briefs, the covers already folded down.

I answered, "And excited at the same time. Partly, I'm nervous because we're crossing this huge taboo line in our relationship, but I'm mostly worried about disappointing you as a lover."

"In what way?" she asked, sitting next to my feet at the foot of my bed, giving me a flash between her legs under the robe of what I assumed were panties.

"For example, if I get the chance to lick your pussy, it's strange to think that I'd be compared to my own mother in that regard. I got some experience with doing it with Cara and she liked it a lot, but Mama Marie's had 20 years to get to know what does it best for you, so I doubt I'll match up. I guess what I mean to say is I'm trying to keep my expectations controlled, neither too grandiose nor too pessimistic and probably still not striking the right balance. Does that make sense?"

"Honey, relax." Sarah slid her hand along my shin, before saying, "Focus on expressing the love we feel for each other. If we're doing that, the rest will take care of itself, I promise. Keep in mind that I haven't been with a man since before you and Tim were born. Marie and I dated men before we got together and were sexual with them, but we've been exclusive to each other for a long time. So, I could worry about being rusty at this and perhaps less experienced in some ways than your girlfriends, but I'm just not going to do it."

"I didn't consider that," I admitted. I paused, then asked, "So, how should we start?"

"Kissing is usually a pretty good place," she answered, chuckling, before she knee-walked across my bed until she was straddling my thighs, then settled onto them. She ran her fingers through my hair before she leaned forward and pressed her lips to mine.

That electric first lovers kiss went on and on, our tongues coming into play as my hands moved to caress her back, first through the robe and then against mostly-bare skin under it, my cock stiff as a rod of iron pressing between us. I couldn't see it while kissing her, but my touch revealed she had on a one-piece teddy beneath the robe.

Before I knew it, Mama Sarah was gyrating her torso against mine, sliding her satin-covered vulva along my stiffness, and she had managed to drag my briefs down enough to expose the head of my cock. I had to break the kiss to warn her, "Keep that up and I'm going to blow my load against your stomach, not inside you where we need it."

"Can't have that," she murmured and suddenly my briefs' waistband was yanked below my balls, her groin was exposed and Sarah lifted and guided me between her labia. She dropped onto me, taking me all the way in with a grunt. She pressed her body against mine again and I felt her nipples dragging along my chest as she rose and fell, separated from me by a layer of satin as smooth as her tight pussy felt around me. I moved my hands to her hips to help guide her motions.

Although I felt things were happening quickly, I knew that cumming into her as much as possible each night during her fertile window was our primary goal, so I decided against making any effort to hold back my first orgasm and came within her after about twenty passes of her slick sheath around me, with my hips thrusting upward as well as I could with my legs still flat on the bed and my back against the headboard. "Oh, fuck, Mama!" I cried, as my cum jetted up into her five or six times.

"Oh, yes, Aaron!" she sighed into my ear as she slowed, my cock still inside her. She rocked her hips in several slow circles and squeezed with her Kegels as I realized she was inducing an orgasm by rubbing her clit against me. Backing away to look me in the eyes, she teased, "Like riding a bike."

Once I realized it was true, I said, "I'm still hard, if you want to keep riding."

"I do, but let's get rid of these clothes first." She had to lift off of me so I could pull my briefs under my butt and down my legs, while Sarah slipped off her robe and I realized the satin and lace teddy she revealed had a pair of snaps at her crotch that she'd simply undone in the same motion when she had pulled my briefs down. She pulled the teddy up her sides and over her head and I saw her totally nude for the first time.

"Gawd, Mama Sarah, you're more gorgeous than I imagined," I exclaimed, burning the vision before me into my memory. Mid-sized breasts high on her ribcage with large protruding nipples, a trim waist that made for a classic hourglass figure, with just a tracing of stretch marks to signify her pregnancy with Tim. A trimmed patch of pubic hair over a lovely pair of outer lips, with her inner lips barely visible from my viewing angle, but glistening with our combined cum.

Sarah smiled. "I've overheard your friends call me a 'MILF' more than once when they thought I wasn't in hearing range. What would they think now?"

"They're never going to know," I answered.

"Smart man, Aaron. They think of the word as a joke, but I doubt they would be as approving if they knew you were actually having sex with me. This needs to stay our secret. As far as the world will know, Marie and I are simply using donor sperm to have two more kids because we're not ready to be empty nesters. Conceiving them in love is a lot more fun, though," she said, as she reached between us to grasp my cock. Giving it a gentle squeeze to check its hardness, she asked, "Ready for round two?"

"Yup."

Letting go, she turned and dropped down to hands and knees, looking back at me while she gave her butt a shake. Viewing her pussy from behind was another moment I wanted to remember forever, her inner lips, wet and ready, peeking out at me between buttocks that were firm from plenty of exercise. Without another word, I took position behind her, notched my glans into position and pushed forward into the wetness I had left from my first ejaculation.

"I love this position," Sarah murmured, as she pushed back at me and we set up a steady rhythm, her firm butt slapping against my legs. I wondered briefly if she and Marie ever used a strap-on dildo with each other, but realized that I would likely have heard this sound at night if they did. Then I felt some shame at picturing Mama Marie in Sarah's place and pushed the thoughts from my mind.

I leaned forward over Sarah's back to reach under her and grasp her breasts for the first time, loving the way her nipples fit between my fingers.

"Oh, fuck!" she cried out. "Just like that, Aaron! Your cock's hitting my g-spot! I'm gonnaaaa cummmmm! Fuck me harder! AAAIIIEEEE!!" She started to shake and I needed my grasp of her torso to keep her from collapsing beneath me, while I resisted the urge to thrust faster into her. After a couple minutes, she took her weight on her arms again, then pushed back at me even harder than before. "I want more... of your cum," she gasped between breaths.

I shifted my hands back to her pelvis and began a hard-quick thrusting into her, pulling her towards me as I worked myself closer to my second orgasm. Pop, pop, pop went our bodies against each other as I felt my explosion draw nearer, until I couldn't have held it back if I wanted. I nearly saw stars as I let loose, pumping more seed into my mother, visualizing one of my sperm meeting her egg to produce a child. Boy? Girl? I didn't care.

Sarah was pulsing around me and I realized that she was cumming again as as her moans and grunts rose in volume. I kept thrusting and when her orgasm was over, we collapsed onto our sides and my cock popped out of her. Sarah turned onto her back and raised her knees. When she turned her head towards me, I kissed her quick, too breathless for anything longer.

"You have nothing to worry about when it comes to your skills, son," Sarah said, when she could breathe evenly again. "I may not have a lot of experience with men, but that felt amazing."

"Thanks, Mama. I didn't want to let you down."

"You and your brother never have. Thank you so much for doing this."

I looked in her eyes and saw her love for me. I asked, "Mama, If you weren't looking to get pregnant, would this still have happened between us?"

Sarah raised her eyebrows. "Once Marie and I knew you were attracted, we would have needed to address it somehow. Taking you to bed so you could live out the fantasy and then move past it would certainly have been one option. Although you would have needed to use condoms to keep us from getting pregnant, since the two of us asking for birth control pills for just a few months would have looked suspicious."

"Have you ever used them?" I asked.

"Our moms put us on the pill as teenagers, but after Marie and I became a couple and we stopped taking them so we could get pregnant with you boys, we never went back on them because we were exclusive to each other and didn't see a need. Thankfully, neither of us have medical reasons to take them."

"And you won't need to go back on them after these babies, either."

Mama Sarah said, "No. Marie and I will be exclusive to each other again, while you and Tim move on to college girls, so there will be no need."

We didn't go for a third round, preferring to let the next nights do the job if the sperm I'd deposited wasn't enough, and fell asleep with her cuddled against my side, her head on my chest.

~~~~~

"So, how was it?" I asked Tim the next morning, when I could get him alone.

"You're asking me how sex with Mama Marie went? I'd rather not go into details, since I don't want to hear them about your time with Mama Sarah, but I don't think it could have gone better as a first time together. We've got two or three more nights in their fertility window this month and I expect it will just get better each night. We'll have to see whether they catch this month and whether they'll let us continue after they're pregnant."

I couldn't help but be disappointed in Tim's answer, as I really wanted to be able to share my delight in being with Mama Sarah, but I also understood why describing it could make him uncomfortable. Imagining him being with Mama Marie made me feel uneasy as well.

~~~~~

Three weeks later, positive pregnancy tests for both moms came as both happy news and a letdown for Tim and I, as far as not having a reason to try again for their next cycle. They had only slept with us on two nights after their fertile window closed and we waited to be able to test.

Neither of us were prepared for what came next, when the true bombshells exploded.

Mama Sarah had a strange smile on her face as we finished dinner after the news, when she asked, "So, are the two of you ready to swap back?"

"What do you mean?" Tim asked.

"To make love to your other mother, of course, now that we don't have to worry about getting pregnant by the wrong son."

"That's incest," I said. "Real incest, the totally against the law kind."

Sarah reached for my hand, before saying, "You've already committed incest, Aaron. You just didn't know it. The one secret we've avoided telling you is who your fathers are. They weren't anonymous sperm donors. You know them both. My brother Mike is your father, while Marie's brother Will is Tim's."

My mind reeled as I jerked my hand away. What did this mean? The erection sprouting between my legs wasn't making it easy to think. Sex with my real mom? Why did that idea both terrify and thrill me so much that I was rock hard already?

Tim made the connections first. Turning to Marie, he said, "You're my Aunt Marie and Sarah is Aaron's aunt. He and I aren't unrelated step-brothers, we're double cousins, right? Roughly equal to half-brothers? Why the hell did you not tell us? Especially before asking us to have sex with you? We deserved to know that we'd be breaking the law before we said yes! And now that you're pregnant, these children are now proof of that crime, should a DNA comparison be done!"

Marie answered, "Which we'll avoid. If it does come out, claiming ignorance of our blood relationship is your best defense. You might think we tricked you, but we were trying to keep you safe, to keep you from revealing your parentage to anyone before we asked you to get us pregnant."

"Safe. Like having a baby with your nephew is safe?" I asked, worried about genetics. "I imagine you think it's safer than having babies with your biological sons instead?"

Sarah answered, "Doing that wouldn't have produced children who are descendants of both of us, so we never considered it. As for the risk from being our nephews, we had our DNA screened and we don't carry any of the recessive genes that the geneticists worry about. There's no more risk than using some anonymous donor. Do you really think we're so foolish that we would have asked you otherwise?"

"We deserved to know, Mama," Tim reiterated. "You let us think that we were your step-sons. Only your step-sons, rather, since we're still that as well as nephews."

"No, you two let yourselves think that," she corrected. "For as long as you've been alive, we've always said that you are equally our sons and we are equally your mothers. No modifiers. That has been our truth as a family. Even if we had told you the truth from the beginning, we would still have treated you as sons, not nephews, from love, not blood. The main reason we kept your maternity a secret was so that your grandparents would treat you like the grandsons you both truly are to them, without having to reveal your fathers' involvement."

Marie said, "Even after we couldn't hide your birth certificates any longer because you would need them to get your driver's licenses, we repeated that you were equally our sons, kept giving you equal treatment and expected the same as your mothers. We never called you our step-sons, not once. You two are the ones who started calling yourselves that, who started to change how you looked at us based on your assumption of our DNA connections. Only the difference isn't between 50% DNA and zero, it's between 50% and 25%."