Back in the late sixties I was sent to live with a foster family. The family consisted of my foster parents and their 5 children, and from day 1, I was treated as if I had been born into the family. The 2nd oldest was Cecilia and she was 1 year older than myself. She was a thick girl. Not fat, just as they used to say "big boned". She was very pretty with long thick blond hair and big pillow like breasts. Growing up I was a real pest to Cecilia always teasing her about wanting to feel her up and see her tits, really she just reacted as if I were a little twerp. On my 18th birthday, there was a knock on my door and it was Cecilia asking if she could come in because she had a special birthday present for me. I said sure, and once she came in, she asked for my birthday if I would like to feel her breasts. I quickly said yes and she pulled me close and said go ahead. As soon as I put my hands full on her breasts over her sweater I felt her knee painfully in my groin. As I yelped in pain I heard my 4 foster brothers burst into laughter - it was a total set up at my expense to get a laugh. Embarrassed I avoided everyone for the next few days. The next Saturday I was in the basement doing my laundry alone when Cecilia came down the stairs. I avoided eye contact as she came up to me and said "Richard I feel really bad about what happened and to make it up to you, you can feel them for real." I sensed another set up, since my relationship with Cecelia was never really any good and I told her so. Cecilia expressed that she was sincere and to make her point she pulled up her t-shirt and exposed the biggest set of tits I had ever seen. I reached out and put my hands full on her breasts and then started rolling her pencil eraser sized nipples between my fingers, the reaction surprised me as she put her arms around me a pulled me closer. As I continued to tweak her nipples, she gave me a glassy eyed look and pulled me into a passionate kiss. I just followed instinct and while kissing I moved my right hand down into the waistband of her sweat pants and into her panties where I felt the fluffy down of her pubic hair in between my fingers. I didn’t just stuff my fingers into her vagina, rather I let my middle finger lightly slide up & down her slit while the two outer fingers teased the folds of her outer labia. Slowly I eased my finger into her sopping wet inner labia and teased her clitoris. Cecilia became putty in my arms as I gently stroked her clit, she started gyrating her hips and her kisses became frantic her tongue darting in and out of my mouth in rhythm to my stroking. I reached down with my other hand and pulled my gym shorts aside and then took her hand and guided it to my rock hard dick. I pulled her pants down to her knees and rubbed her clit with my thumb as I used my middle and index finger to massage the inside of her vagina. Cecilia’s stroking of my cock became firmer and faster in time with her own grinding on my fingers. I couldn’t hold back and my dick exploded with huge spurts of come all over her thick blonde pubic hair and at just that moment her whole body stiffened and started shaking. Her legs became like rubber and we both fell into a pile of laundry kissing as I continued to lightly rub her clit. As we lay there kissing, she said that she had never had any sexual experience before this and had no idea of what an orgasm was. We straightened ourselves up and went back upstairs, with just another kiss before we got to the top step. My relationship with my foster sister involved further adventures over the next few months before I joined the Navy. If you’re interested, I will gladly share some of those in later submissions.