I have a sister who is very pretty. Even as a kid I used to look at my sister and think she was good looking. We never teased each other and were never mean to each other. We had a great brother-sister relationship.
When we were about fifteen we started talking to each other about sex. She was obviously getting interested in boys by then and I was getting interested in girls. By the way, she is one year younger than me. We had never walked around the house nude or anything like that. I hadn't seen her naked since she was about five.
One day, while talking about sex, she asked me questions about getting hard-ons and how exactly it happened...needing manual influence or was it involuntary? etc. I explained usually it was quite involuntary! I then told her that sometimes if I was by myself and wanted to be hard I had to stroke it to help it up. My sister then asked me if I ever masturbated. I was kind of embarrassed but I said, 'sure.' I asked her if she masturbated and she admitted she did too.
I actually could feel myself getting hard as I talked about this with my sister. Then, she just came out and said 'since sex is new to both of us and you haven't been with a girl and I haven't been with a guy, would you mind if we learned a few things together about sex?' I asked her what she meant, although I could see where this was going! She then said, I'd like to see you totally naked and study your body, and if you want to study mine too that's OK.'
That was all it took. My dick went BOING! I said I would like that very much. We didn't kiss or anything like that. We just started getting undressed in front of each other. We finally stood facing each other totally naked. Her eyes immediately went to my throbbing hard-on and my eyes raced back and forth between her nice breasts and nipples to her moderately hairy pussy. Wow, my sister looked good!
She said 'I want to really LOOK at you' and she pushed me back until I sat on the edge of the bed. She got on her knees and inspected my hard dick, running her hand up and down it, squeezing it and marvelling at it's hardness, feeling my balls, everything. 'Gosh, you are so HARD!' she said. She was surprised by my thickness and length too. She had no idea a penis could grow so much. She tenderly felt the head of my dick and she asked me what felt good when I masturbated. I took my dick in my hand and showed her how I stroked it, and I showed her a couple of ways I hold it. As she was inspecting me I was looking down at her beautiful bare tits and I reached out and caressed them.
It was now my turn to examine her. She laid down on the bed and spread her legs wide open and let me lay with my face between her legs. She used her fingers and explained all the parts of the vagina, and demonstrated what felt good to her. She said it was OK for me to feel her so I started running my fingers through her pubic hair and down her lips, and I slid a finger inside her pussy. It was so warm and wet. I studied her pussy for a long time. My dick was throbbing too. I asked her to show me more of how she masturbates and she began rubbing her clit, and sometimes going inside for wetness. It was awesome to watch her. I again noticed her breasts and I felt them again as she laid on her back, noticing her pink nipples, and I began sucking them. She moaned that felt good as she was masturbating. Before she came though she said I needed to masturbate too because she wanted to see me cum. I knelt between her open legs and started jacking off as she watched and masturbated at the same time. I told her I was about to cum and she watched intently as I squirted cum all over her stomach. She came too and she shuddered and shook the bed. She took a hand and wiped my cum and smelled it and rubbed it between her fingers.
We cleaned up and dressed and told each other it was 'interesting and educational...and FUN!' For years we masturbated together many, many times. It slowed down when we were in college, but we still managed about one session a year. She eventually got married and I did too and it stopped completely.
About one year ago when I was 54 and my sis was 53, we found ourselves talking about our childhood and all the fun we had. I told her how much I loved our masturbation times and I asked if she ever thought of them too. She said yes, she definitely did and she still masturbates to those memories. I admitted I did too. I was nervous about asking this since we were both married with families, but I said I would love to do it again. She smiled, turned her head away, maybe in embarrassment or thought and she said she would do it again.
We agreed on the following day when we could be alone. I went to her house and talked about it more, then she stood and stripped in front of me and I in front of her. Our bodies are certainly not in the good shape they were in then, but my sister is still beautiful. Her breasts are bigger, her nipples appear larger, she has a much bushier pussy now, and she could lose ten pounds but who cares! So could I! She held my hard on and talked about it and she stroked it, and we got comfortable and watched each other masturbate as well as helping each other do it. Like so many times before I came all over her stomach and breasts and she had a heaving orgasm. We cleaned up and hugged warmly, and she said this wouldn't ever happen again, so I will cherish the memories for the rest of my life. What a wonderful sister I have. We helped each other learn a lot about the opposite sex at a time when many other kids were fumbling with themselves in the dark!