Wrong!

''Beth I can't.''

''Why not?''

''Because it's wrong.''

''I know it is.''

''Well then.''

''So it's wrong to wank you but it's more wrong to touch my tits?''

''No but...''

''Ok. Do you want to?'' she asked, placing a hand under each breast and jiggling them.

''Yes but...''

''Oh just do it!'' she shouted.

That made me laugh, for some reason. I paused for a moment then leaned across and gently touched one of her nipples with my finger tip. We both reacted at the first touch as if there had been a small electric shock. I touched it again. Then the other, then both at the same time. Several minutes of touching and groping and fondling followed. I was beginning to relax. The immorality of the situation was receding further to the back of my mind.

My next act sealed the deal. With the thumb and index finger of my right hand I casually flicked her left nipple.

''Oww!! What was that!?'' she said laughing.

''Oh sorry.''

''Don't be. I liked it.''

''Did you. I do it to Sophie sometimes. Usually to piss her off. She hates it!''

''I liked it. A lot. Do it again.''

So I did. Several times. As I continued to play with my sisters breasts I realized her hand was down between her legs. I realized she was touching herself!

''Are you...?''

''Yes sorry. Don't stop now please.''

And so I leaned in and began sucking her nipples as she masturbated. Her orgasm soon followed and after, for the first time that evening, she looked up at me, slightly embarrassed. We sat in silence, then got dressed in silence, walked to the car and drove back, still in silence.

It was only when we were about five minutes from her house she spoke.

''Mark?''

''Ummm...?''

''Thank you.''

''For what?''

''You know.''

''Err...''

''That. You know. That. Thank you for...that.''

''Well thank you as well.''

We laughed as we neared the house.

''Definitely keep that a secret,'' she joked as we pulled into the drive.

We went in and acted normally as we chatted to our parents. I drove home later, still trying to get to grips with what had happened.

+++++++++++++++++++++++++++++++++++++++++++++++

Sunday.

I went around to my parents house to help Beth with more revision. My wife Sophie had called from her conference and suggested that I go by bus to my parents and she would call by and collect me on the way home that evening.

I had lunch with Beth and mum and dad. Beth wore a short light blue skirt and a cropped white top. Sleeveless and cropped to just below her breasts. A white bra occasionally visible underneath. Daring. But not inappropriate.

After lunch I sat with mum and dad in the garden for a while. Beth went up to her room and said she would come down when she was ready to study.

When she appeared the first thing I noticed was that the bra had gone. Just visible below the cut off of her top was the slight rising flesh of her breasts. Great. What would our parents think. I followed Beth down to the den.

We began studying. She seemed to want to study and I did my best to ignore her skimpy clothing. We made no mention of the previous evenings activities.

After an hour or so of surprisingly focused revision we heard footsteps coming down towards the den. There are two short flights of wooden steps down to the den so you can always hear people coming down. I remember that had been particularly useful for my sister and I when we were teenagers whenever we had a boyfriend/girlfriend over and were up to no good! As mum approached I smiled as I imagined Beth or Robbie with a 'friend' thinking just the same as me or Kate all those years ago.

Mum came in.

''Do either of you want a drink? It's so hot.''

We declined and mum took the hint, leaving us to the studying. As she left mum neglected to close the door. I smiled again as I remembered how she used to do that when I was young. Beth stood up and went to close the door. With her back to the wall she looked at me. I looked back, my eyes widening as she pulled up the front of her top to reveal the breasts I had become so acquainted with the night before. With her top bunched up around her shoulders she walked back toward me.

Instead of sitting down she stood in front of me. I instinctively moved to fondle her small titties before settling down to suck on them. I even allowed myself a couple of flicks on her nipples, still thrilled that this pleased her in a way it annoyed my wife.

As I sucked on her tits my hands wandered round to ass. First outside her skirt, then onto the backs of her legs then finally up inside her skirt to her ass cheeks. No panties. I should have guessed.

I pushed her skirt up clear of her ass and slipped one hand between her legs and against the folds of her pussy lips. We were getting carried away, my stiff cock pushing against my shorts, when suddenly footsteps on the wooden stairs alerted us to a problem.

The footsteps were loud and fast. Beth adjusted her clothing and sat back down just a second before Robbie and his friend Ben came bursting through the door. Robbie had stayed over at Ben's the previous night.

''Robbie! Knock!'' scolded Beth.

''Sorry sis I forgot.''

''Hi Beth. Mr Johnson,'' said Ben, politely.

They got the toys they had come looking for and were back up the stairs almost before they had come in.

''Now where were we?'' Beth smiled as she got up to close the door.

''Revising Beth. Just revising.''

''Spoilsport.''

''Well one of us has to be.''

We did our best, revising for another hour or so. I think the desire to fool around was bubbling just under the surface for both of us, but we managed to keep a lid on it. Finally though we cracked. Beth went upstairs to get us some drink. When she came back in she placed the drinks on the table and went to close the door.

With the door closed she stood in front of it. She lifted her top, up and over her head.

''Beth. No.''

Ignoring me her skirt came down. Holding her clothing she walked naked towards the table. She went past her chair and stood in front of me. Then she turned her back on me and lowered herself onto my lap. My cock pushed against my shorts and prodded her.

''You were saying?''

''I was saying no,'' I said as I wrapped my hands around her breasts.

My right hand slipped towards her waist, feeling her very neatly trimmed bush.

''When did you get so dirty?'' I laughed.

''It's you! Kevin and I mess around. We have sex and stuff but...''

''But what?''

''Stop asking questions. Just do what you're doing.''

What I was doing was slipping my finger into her pussy.

And then footsteps. Fuck!

''Mark! Sophie's on the phone for you upstairs.''

It was dad. At least he had stopped halfway down the stairs.

''Thanks dad. Coming!'' I called as Beth stepped off me and began to dress.

I spoke to my wife. She was about an hour away. I asked mum if Sophie and I could stop for dinner. That was also the point for Beth and I to stop revising and whatever else we were doing.

Sophie arrived and we all enjoyed a family dinner. I don't know if I was the only one to spot that Beth still wasn't wearing a bra under her cropped top.

That night at home Sophie and I lay in bed. Naked as always.

''So how was your weekend?'' we asked each other.

She told me about her conference. Boring. Dull. I told her about mine. Helping Beth with her revision. And I told her about the drive to Eagle Falls. I left out certain parts.

''I must take you there one day,'' I mumbled to her.

After a particularly energetic sex session we lay together.

''Fuck! You were a hungry boy tonight!'' exclaimed my wife.

''I'm always hungry for you baby.''

''No tonight you were really up for it. What's got you so excited then?''

''Just missed you I suppose.''

+++++++++++++++++++++++++++++++++++++++++

Unlike the previous week I felt none of the awkwardness whenever I saw my little sister around school. More a sense of euphoria. Every time we passed in the hallways I could detect the slightest of smiles on her face. Normally she would look at the floor until I had passed!

In my history class on Wednesday our eyes would occasionally meet and we would allow ourselves the most subtle smile. The only time I felt a slight pang of guilt was when I taught my younger brother Robbie on Tuesday.

On Wednesday evening I phoned my parents home. I hadn't arranged a time to give Beth her revision help and while not wanting to appear desperate I was keen to be with her. Dad suggested Thursday evening as mum takes Robbie to guitar classes every Thursday and so the house would be nice and quiet with just me, Beth and dad. Perfect.

Thursday was another very hot day. This was turning into a fantastic summer. After dinner with Sophie I drove to my folks house. Dad answered the door wearing just a pair of shorts. Not an attractive sight. He led me through to the garden.

''Beer?''

''Thanks dad. Where's the student?''

''Upstairs. She'll be down in a minute.''

Moments later Beth appeared wearing a bikini. I tried to play it cool but my heart was already skipping.

''Can I get a beer please dad?'' she asked.

''Just the one young lady and don't tell your mother.''

We sat at the table in the garden for a while and chatted, before Beth announced she was going to her room to get her books to begin revision.

''Meet me in the den. I'll be right down,'' she told me.

Before I went downstairs I took off my shirt, and placed on the chair in the garden.

''It's so hot isn't it son? Supposed to get hotter for the weekend they reckon.''

In the den I sat at the table, in the chair facing the door. Beth appeared still in her bikini, carrying a pile of books. Instead of sitting in a chair she proceeded t come around and sit on my lap. I instinctively wrapped my hands around her stomach.

''So what are we revising today, young lady?'' I asked her.

''History.''

''Oh history. Really.''

''Uh huh.''

''And are you any good at history?''

''Not really.''

''And why's that?''

''Well the teacher is a bit of a dick.''

''Really? What's wrong with him?''

''He's a bit old.''

''That doesn't make him a dick. What else?''

''Well I think he's a bit of a perv.''

I was beginning to enjoy this game.

''A perv? Why do you say that?''

''Well he's always looking at me kinda weird. Like he fancies me or something,'' she laughed.

''Really. I thought he fancied Marcia Brook.''

''Mark!! You don't?''

Marcia Brook was a girl in Beth's class. I know teachers shouldn't ever, ever think that way but I always thought she was a bit hot.

''Maybe. Maybe not anymore. I might have lost interest.''

''I'll tell her.''

''Don't you ever.''

''How are you going to stop me then?''

I said nothing, simply slipping my hands up to cup her bikini covered breasts.

''Hmmm that might work. Keep going.''

''I like your bikini by the way.''

''Thanks. Pervert.''

''Is it the same one you wore that first trip to Eagle Falls?''

''Yep. I only have two bikinis. The other one I can't wear.''

''Why not?''

''Mum won't let me. I bought it for our holiday to Mexico last summer, but mum says it's not suitable.''

''Oh?''

''It's seriously skimpy. I mean seriously. It's white, like a boob tube top, no straps and the bottom is a thong. But it's a really really skimpy one. I'm not even sure why I bought it.''

''Sounds sexy to me.''

''Yeah I meant to take it back but never got round to it. I wore it for Kevin in the garden here a month or two ago. He ended up fucking me right out on the patio!''

''Wow!''

''Maybe I'll wear it for you one day...''

Our game was stopped by dad coming down the wooden steps to the den. I shifted to get Beth to move off my lap but she held firm. Dad walked in and looked at us.

If he felt any surprise at seeing his teenage daughter sitting on her older brother's lap, wearing just a bikini, with his arms around her stomach, he hid it well.

''You left your beer in the garden. I thought you might want it.''

Oh thanks dad.''

''So what are you revising tonight?''

''History dad,'' sighed Beth.

She sensed that dad and I would slip into a year long discussion at the mention of history. She was probably right. We usually did.

''Oh history. Which topic?''

''The second world war. Or Pearl Harbor in particular,'' Beth explained.

''Oh, fascinating stuff.''

''Yeah sure,'' Beth whined sarcastically.

''She doesn't rate her teacher,'' I joked.

''I imagine it must be hell teaching this one,'' dad laughed, pointing at Beth.

''She's a bit of a tease,'' I joked.

''Thanks Mark.''

''I bet she is. She always is at home. I think I might have a book upstairs about Pearl Harbor. I'll have a look later.''

''You could look right now dad. I'd love to see it,'' lied Beth, pulling a really petulant teenage girl face.

Dad went off. Beth and I laughed. She wriggled about on my lap, feeling my erection.

''Oooh you've got hard,'' she smiled.

I gripped her tits harder and tried to slip my hand inside her.

''Wait till dad's finished popping in and out,'' she scolded me.

''When he comes back in I'm gonna keep my hand here,'' I said, squeezing her left breast from outside her top.

'' I bet you won't.''

''Trust me.''

''No chance. I dare you to though.''

''A dare? And if I win?''

''Then I'll suck your cock.''

''Oh. Right. Wow. If I lose?''

''I'll tell Marcia thingy that you've got the hots for her.''

''I never said that!''

Anyway dad soon reappeared, clutching some old history book. My hand remained firmly on the left cup of Beth's bikini top. My other hand still on her stomach.

I looked at dad's book and we chatted for a while. He told Beth about Pearl Harbor, but none of it was really appropriate for her exam.

''Dad, they've changed the way they teach nowadays,'' I butted in, my hand still in place.

''How can they teach history in a different way? History is history.''

I'd had this conversation a million times with dad. He just couldn't comprehend that teaching had changed in the twenty years since he left the job.

''Show me that book then,'' he moaned, pointing at Beth's text book.

She slid it across the table to him. He picked it up to look at it but he didn't have his glasses. He stood up to go and fetch them.

''Back in a minute.''

''Sorry about this,'' I said to my sister.

''I knew it was a mistake to do history. I hoped dad would stay away.''

I squeezed her breast.

''You get your blow job then.''

I laughed.

''Let's take it a stage further,'' she said.

''Huh?''

''Put your hand inside my bikini top. I want to feel you touching my tit when dad comes in.''

I was about to argue that it would be too risky when we heard dad coming down the stairs.

''Quick,'' she said, taking my hand and stuffing it in her top.

Dad walked in, not looking at us. He put his glasses on and sat reading the book in silence. As the minutes passed, I felt braver. I began to squeeze Beth's tit and rub it a bit. More minutes passed. Beth amazed me by pulling the bikini cup down, exposing my hand on top of her tit. Dad was totally unaware. He carried on flicking through the pages. I pulled my hand away for a moment, completely exposing her left tit. Beth quickly grabbed my hand and put it back.

Finally dad grunted a couple of noises, not really words.

''Dad. Can I have my book now? I've got my exam next week.''

''Uh? Oh sure. Sorry. Mark you and me must have a discussion about this as soon as we can.''

''Oh great I'll look forward to that.''

He put the book towards us. I stuck out my hand to grab it, uncovering Beth's breast but thankfully dad didn't notice.

After he'd gone we burst out laughing.

''You know I don't really need any help with my revision,'' my sister sighed, climbing off my lap.

''I know you don't. I realized that a week or so ago,'' I laughed as she knelt down in front of me and pulled down my shorts, exposing my erect cock.

She wrapped her lips around my shaft and began to lick it. Soon I was enjoying a beautiful blow job from my sister.

''I'm gonna cum soon. Oh god oh yes oh Beth oh god oh!!'' I moaned in increasing volume as I got closer.

She swallowed every drop of my cum and licked my penis clean.

I looked at my watch. Five past nine. Mum and Robbie always came home about nine thirty.

''When are you gonna come here again?'' asked Beth.

''Not sure. I need to check with Sophie. She gets a bit moody if I'm over here too often.''

''How about Saturday? Mum is staying with her aunt that night.''

''Actually Saturday could work. Sophie is going out with some friends that night. She doesn't usually come in till about two or three in the morning.''

''Great. I'll try and persuade to Robbie to stay at Ben's that night.''

''How? Don't make it too obvious.''

''Oh trust me. I have my ways of persuading our little brother.''

''What about dad?''

''Dad's ok. He's in his own little world. You know.''

''Ok Saturday then.''

+++++++++++++++++++++++++++++++++++++++++++++++++

On Saturday I took a risk. I never told Sophie I was going over to see Beth. I waited till she had gone out then I drove over. Dad answered the door, wearing just his shorts again.

''Hi Mark. I wasn't expecting you.''

''Oh? Oh Sophie went out so I was at a bit of a loose end and thought I would see if Beth needed any more revision help.''

''Oh that's kind. Honestly that girl doesn't deserve you. I'm not even sure she's in. I know Robbie has gone to his friend's house. Hang on a minute. Come in come in.''

Dad stood in the hallway and called out twice, first towards the stairs going up and then to the stairs leading to the den.

''Beth!! Beth!!''

A moment passed then to my relief Beth appeared at the top of the stairs.

''What?''

''Oh there you are. Your brother's here. Revision?''

She was wearing a summer dress. White and pink. About thigh length.

''Oh hi Mark.''

Good acting.

''Hey sis.''

''Erm I'm not really in the mood to study tonight. I was going to watch a movie down in the den.''

''Oh.''

''You can join me if you want. Unless you've got a better idea.''

''No no that's a cool idea.''

''Come and have a beer with me in the garden son,'' suggested dad, putting his arm around my shoulder and gently leading me to the garden.

Beth followed and sat with us at the table.

''Dad can I have a beer please?''

''Just the one little girl. As always. And don't forget...''

''Don't tell mum!'' she laughed.

She got herself a beer and placed it on the table.

''I'll just go and change. It's so hot.''

She went back in and a few minutes later appeared at the kitchen door wearing what if someone actually finished making it could be described as a bikini. It was as she had described, only skimpier. If she was naked it wouldn't have been any more shocking. The boob tube was thin, covering her nipples but not the whole cup of her breast. The thong was a thin lace along the top, a thin strip covering her pussy lips and I can only imagine a thin strip in between her ass cheeks. They actually made such things?

She sat down before dad noticed. She sat opposite me and smiled, realizing I couldn't stop staring at her.

''Beth be a love and get me another beer would you? Mark are you ok?'' asked dad after fifteen minutes had passed.

Beth stood up and walked to the kitchen. Her ass was totally uncovered and visible. This time dad did see her.

''Good god! Young people now. What do they wear?'' he asked.

''Oh I know. Crazy.''

''That sister of yours, she wears the strangest clothes. No shame. In my day people wouldn't dream of wearing the things they do today.''

''I can imagine.''

''You must see it at the school. Young people!.''

''Yes dad.''