There we were on the sofa, relaxing after a pleasant meal, glasses of wine in hand. Bethany, to give her her proper name, had swung her legs up on my lap, allowing me the pleasant prospect of stroking her smooth thighs. "Hmmm" she purred "that's nice." She wriggled down a bit further, causing her dress to ride up, revealing the edge of a lacy white thong. My hands travelled northwards... Suddenly, Beth giggled. "Do you remember that time Mum caught us at it?" How could I ever forget?

******************

We were in my bedroom. There was thirteen-year old Beth, on her back on the bed. School blouse undone showing her pert little boobs with their well sucked nipples., skirt up round her waist and her legs spread. Between them, me, her fifteen-year old brother with my cock buried up to its root in her sweet little cunny. Then, in walked our Mother.

"What do you think you're doing?!!?" she shrieked. I took this to be a rhetorical question.

"You're disgusting!" A bit harsh I thought as weren't being kinky or anything.

"What would your father have said?" (Still at the top of her voice.) An interesting question, given that he'd taken Beth's virginity a few days after her tenth birthday. Mind you, she was complicit in this action. Dad had been bathing her for years and as she'd got older, Beth had been, to be honest about it, getting him to masturbate her when he did. He eventually started to wank at the same time, leading to heightened enjoyment for both of them. One night, Beth said "Daddy, will your thing fit in my hole?" Dad was evidently a bit hesitant but in the end he succumbed, just as Beth had intended. She told me afterwards it hurt a bit but the feeling of him coming inside her more than made up for that. Sadly, Dad was killed in a car crash a week later so it never went any further.

"I just hope the neighbours don't find out!" Well, that depends on which ones Mother had in mind. Little Fiona from next door, who was two years younger than my sister, hero-worshipped Beth and would do anything for her. We had both been molesting Fiona for months and she enjoyed every minute of it. She often went home after an afternoon in the playhouse at the bottom of our garden minus her knickers and with her slit dribbling spunk. Also ,Beth was convinced the old man whose garden backed on to ours, used to toss himself off as he watched her sunbathing in the garden. Not that I would blame him if he did, as I did too. But then, I had access to Beth's laundry basket...

Mother demanded to know how it had happened. "Well, er.." I began, then Beth said "We talking about school and started teasing each other, then we sort of got carried away. A bit, well more than a bit. We haven't done anything like this before." She said all innocent, while I waited for the sky to fall for such a whopping lie. We had been having sex as often as we could for the last three years!

We started after my sister had come into my room one night when we were both supposed to be in bed. It was about a month after Dad had died. She was quite sad and told me what she and Dad had been doing, the bathing, masturbating and the sex. I tried as best I could to comfort her but a twelve-year old boy isn't very good at that sort of thing. Then my sister suggested I took over what Dad had started. So we began having sex, usually in the playhouse but in the house whenever we could. Often it was after school, or, if we were really horny, in the alleyway between the bus stop and our house. Beth would get herself wet sitting on the bus, so that when we got the alley I could pull her knickers aside and slip my cock in easily. My sister would bite my shoulder as I fucked her to avoid crying out.

"Honestly Mum, we won't do it again" I hoped that this was another lie by Bethany and that the missing part of the sentence was "when you're likely to catch us."

Luckily, that's what happened. We managed to calm Mother down and, like any family secret, it was never referred to again.

*********************

That all happened more than ten years ago. This evening, my sister and I had a laugh about if and then I started to stroke the front of her slit. There's no-one to "catch us at it" here in her flat as Beth slips her thong down and lifts up her dress. So, now, like before, I have my cock buried up to the root in her sweet little cunny...