I posted the story of sex with my eldest sister under this same heading.
This is the next stage of my story with my sister that is 11 months younger than me, her name is Maggie.

After my oldest sister left home and I was whacking my cock 3-5 times a day I needed to get more pussy, bingo...my sister started playing around with me when she was 12 and I was late 13. First it was just being kids exploring our bodies but quickly changed when she became 13 and her boobs were popping out of her bathing suit as was my pecker while playing in the "stock tank". Wasn't too much longer that we actually had sex and it did happen in that same stock tank. we both loved what had happened. During that summer we must have fucked 50 times. Hard to believe that she didn't get pregnant, but then neither did my older sister Mary. All through HS she and I fucked at every chance we got. Sometimes when we were 15/16 it had gotten to the point where we were having sex as much as 4-6 times a day. We would even fuck at school behind the gym but that was maybe only 4-5 times when I was a sophomore and she was a freshman.
We fucked all through high school, even when she got herself a boyfriend. It slipped once that we were fucking regularly to her boyfriend and that is when we started getting into some more kinky sex. It was great because that guy liked to watch us and of course we liked being watched. Sometimes he would play with her boobs while we were engaged in sex, or he would finger her. When we were in my senior year and she was a junior I had her used in the back of dad's 55' Ford pickup by 6 different boys at a school dance. Talk about pulling a train...well she sure did and that was her first time. In the meantime I had fallen in love with this sweetheart of a girl that was 2 years younger than me. Her and I would sneak off into the mountains on horseback and fuck for hours then send her home to her daddy. My sister followed us once and she waited till I was deep in MM's pussy then Maggie walked up on us, MM freaked out bad. But Maggie told her to calm the fuck down and let's all play together. It took a few minutes for MM to get into the swing of things, but when she did she showed us that her Irish genes were fully kicked in. We fucked numerous times after that as a 3some. But when I graduated high school and moved to the BIG city we lost contact. Instead Maggie followed me to the city and lived in my apartment her summer prior to being a senior. We fucked everyday and more that summer till she had to go back home to finish HS. After that it wasn't long before I got called up to go to the Army and ended up in Vietnam, so then we hadn't fucked for at least 3 years till I got out and she let me crash at her apartment here in the city, she had 2 roommates. It was like being back on a bicycle, once you learn it you never loose it. Best part was that I spent most of those 2 months I lived there fucking her roommates more than I did Maggie. After that we never have fucked again. came close a couple of times while watching porn with her and my wife and her hubby...