The apple doesn't fall far from the tree, or so the old saying goes. It certainly proved true with Louise; obviously, she and her sister took after their mum sexually. And I should know, I've bedded them all. Obviously, Louise knew about me and Shona, as she eavesdropped on us fucking when we dated. But I couldn't have imagined how horny her mum would prove.

I first started dating Shona when she left high school at eighteen. We were regularly having sex for the two years we were together. Her sister was seventeen months younger and by her eighteenth birthday, she was openly flirting with me and had lost her virginity.

Louise's dad suffered from ill health; unfortunately, this bout had landed him in hospital with a serious chest infection. So, most nights were spent visiting hospital, then taking Kate home and seeing her settled in.

On this afternoon, Loiuse asked if I could do a favour; could I take her mum to her dance class, and she and Shona would visit dad in hospital. I said yes, I'd happily drive her mum and pick her up afterwards. Then Louise asked if I'd be Kate's partner for the night? Now, anybody that knows me knows I'm no dancer, but I told Louise I would drive her mum, and if she was ok with it, I'd be her partner. She thanked me, then told me to wear a collared shirt, dress trousers and not trainers.

So, at six-thirty, off I went to pick up Kate. As I pulled into the driveway, Kate stepped out to meet me, and she looked pretty tasty in black high heels, tan stockings, black pencil skirt, and a tight white blouse which showed off her ample breasts. I must admit, I was a little aroused.

We arrived at the class, and Kate introduced me as her son-in-law. She then instructed me in the proper manner to hold her for the dance. This required me placing one arm around her waist, my hand resting on the top of her bottom. I was cautiously holding her.

"Robert, for goodness' sake, hold me like a woman; this dance is supposed to be romantic," she said. She pulled me closer to her, pressing her ample breasts against my chest. As the class progressed I felt myself relaxing. I let my hand slip down to grope Kate's bottom.

"That's it, Robert, pull me close, cheeky," she whispered.

I allowed my hand to cup her arse cheek, and as we swayed to the music, I allowed my finger to trace the outline of her panties.

"Mmm, yes, Robert, that's nice," she purred. "I can feel you're enjoying this," she whispered. And I definitely was; my cock was rock hard. What was I thinking? This was my wife's mother, and I was feeling her arse. Yet I couldn't help but pull her tighter to me, pushing my erection onto her.

"Naughty, naughty boy," she whispered. "Maybe I should spank the naughty boy?" she went to whisper but instead flicked her tongue into my ear. I was now slowly massaging her bum cheek.

"Oh God, yes, that's so good, Robert, you bad boy," she moaned quietly. As the dance ended, she gave me a little kiss on the cheek and patted my bottom.

"Well done; I think you enjoyed that, Robert," she said, smiling at me as she headed out the door.

The drive home was tense, with very little conversation. However, what was noticeable was Kate resting her right hand on my groin, gently rubbing my crotch. All my experiences were telling me she wanted my cock, but this was Louise's mum, my mother-in-law, and my brain was saying no. But my erect cock was saying yes. Go for it or not - that was my conundrum.

We finally arrived at her home, and I walked Kate to the front door. She walked in front, her arse wiggling in her tight skirt.

"Do you want to come in, Robert?" she asked.

"Yes, yes, I do," I replied, slyly groping her arse cheek. She then took me by the hand and led me inside. In the hall, she turned to face me and kissed me full on the lips - not a maternal kiss, but a full-blown snog, sliding her tongue into my mouth. As I pulled her tighter to me, we both entered the lounge and sat on the couch. We were hungrily kissing. I was groping Kate's breast as she slid the zip of my trousers down to free my erect cock. My other hand slid up her leg, searching for the front of her panties.

Kate then lowered her head to take my cock in her mouth. She was good, taking my whole cock, then flicking her tongue over the head of my cock before sucking its whole length again. I was gasping in pleasure. I was unbuttoning Kate's blouse to expose her white bra encasing a fine set of tits. I now decided it was time to take the lead. Kate was getting fucked.

I pushed Kate back onto the couch, pushed her skirt up to her waist to expose her white cotton Granny panties, and yes, she was wearing stockings and suspenders. I eased her panties down and off and hungrily started to eat her hairy pussy. Kate was lying back with her legs over my shoulders, purring in ecstasy as I licked and probed at her pussy.

As she lay back, moaning in pleasure, I couldn't help myself and inserted my middle finger into her tight bum hole. Kate squealed in shock, but she didn't stop me as I pushed my finger deeper while flicking her clit with my tongue. I assured her quietly that this would be a turn-on for her, and slowly she began to relax. As I licked at her pussy, she groaned in ecstasy and began to push her bum back to meet the thrusts of my finger. I felt her breathing quicken, and as I nibbled on her swollen clit, I felt her body stiffen as I sensed she was ready to come. So I inserted a second finger into her tight arse - and suddenly she burst into orgasm.

"Fuckin' yes, that was awesome, Robert, but I want your cock, honey. I want you to ride me," she said.

I realised this was wrong. I had just fingered my mother-in-law and eaten out her pussy, but it was sooo good.

"Kate, I'm going to fuck you, but I want to do it doggy-style. Please get on your knees," I asked. Kate got down on all fours and I positioned myself behind her. I had eased her tits from her white bra, as I wanted to see her tits swinging as I fucked my wife's mother. Kate had reached behind and parted her pussy lips as I eased my cock into her. I was building up my rhythm with long, slow strokes to start then, quickening till I was pounding my cock into Kate.

"Yes, yes, Robert, that's it, ride me, please, make me come again," she moaned. As I pumped Kate, I leant forward and whispered in her ear.

"Will you take it up the arse? I promise it wont hurt, and you will love it. Your daughter does."

"Please be gentle, Robert; I've only done this once. If it's sore, please stop," she implored. I could feel Kate tense up as I knelt down behind her. Using love juice from her moist pussy, I began to lubricate her tight arse. I then slipped my tongue into her bumhole, flicking my tongue on her tight bum before sliding it deep into her arse.

"Oh my, that feels so good in my bum," she sighed.

I placed both my hands on her hips and gently eased my cock into her bum cheeks.

"Oh god, oh god, that is so big," she gasped.

I gently eased my cock in till my full seven inches filled her arse.

"Mmm, that feels so good, Robert, but please be gentle," she begged.

I was slowly sliding my cock in and out with long, slow strokes while Kate pushed her bum back to meet my thrusts. I could feel her relax as I began to quicken my pace of fucking.

"Yes, Robert, that's it, ride me, I love it, pump me, pump my arse," she moaned through gritted teeth.

I began to quicken my pace and was now slamming my cock hard into her. Her tits were swinging as I pounded Kate's arse. As we fucked, I reached round and started to play with her swollen clit.

"Yes, yes, Robert, that's fucking amazing, oh god, please make me cum," she begged. I continued to flick and rub her clitty with my fingers as my cock slammed into her arse. Kate was quietly sobbing in ecstasy as I pushed my cock in its full length.

"Oh yes, yes, please honey, please give me your man juice, son, make me cum," she pleaded.

With one final push, I felt my cock stiffen and then a large stream of sperm shot deep into Kate's arse. I felt Kate's body stiffen under me, then she shuddered into orgasm herself.

We both collapsed on the floor, tired but content. But now the panic and worry set in as the realization dawned that I had just fucked my wife's mother up the arse. There was no way Louise could know about this; it could destroy our marriage. I had to get Kate on my side.

"Kate, I don't regret what has happened tonight, but this is so wrong. I'm married to your daughter, and I would never cheat on her. I love her," I stammered quietly.

Kate had a mischievous look in her eyes as she replied. "Do you seriously think that I'd fuck my daughter's husband? I know all about your and Louise's sexual arrangements; this was all her idea, honey. She knew her Dad had no interest in sex, and she knew I was sexually frustrated," she informed me.

I couldn't believe what I was hearing, but as I let it sink in, it began to make sense.

Kate had never showed any affection to me previously, always coming across standoffish. I had previously put this down to the fact she knew I had bedded both her girls. Yet, now, here we were, literally minutes after having great sex, and all at my wife's prompting and with her permission.

"Thank you, Robert. Louise was right when she said you would be hesitant about this, but you can't resist when a woman comes on to you. And yes, my daughter was right; you are a good fuck,"

I was totally gobsmacked; both of them had set me up and manipulated me perfectly.

As I drove home in the car, I chuckled to myself and laughed. I couldn't help but feel that Kate's two daughters were just like their mother.