I had always noticed and longed for my sister’s body. She had C-cup breasts and a nice big ass. When this story started I was 15 and my sister was 14. My sister just started having her period and was starting to ask questions about sex. Our parents were always at work and it was summer break. All of our friends were on vacation so she had to ask me. She asked if sex was dangerous and I told her there were some diseases, but she wouldn’t have to worry about them unless she had sex with someone who had it. She asked if I’d ever had sex. “Of course” I said. She asked if it felt good and started to blush. I told her it was the best thing in the world. She asked if I would show her how to have sex. I knew it was wrong but she is so hot. Then she asked if she could get pregnant. At the time I didn’t know that she was having her period so I said no it will be fine. She started to get undressed and so did I. I couldn’t stop staring at her tits and ass. I told her she looked gorgious. When I whipped out my cock she gasped. “It’s so huge” she remarked. I told her that theres a couple different kinds of sex. There is oral and theres regular below the belt sex. “What is oral sex?” she asked. “It’s when a girl sucks a man’s penis or a man licks a girls vagina or pussy,” I replied.