It all started about 2 years ago. We were both drinking and talking about sex. Both of our significant others were out of town at the time and we live right next door to each other. We act like normal siblings should every day. Well that first time talking awkwardly about sex for some reason with a few drinks in us of course we both asked the question: I wonder what it would be like. So we went at it right there on the couch, awkwardly and hesitantly of course kinda of daring each other the whole time. There was no foreplay or anything she is on the pill and I wore a condom. It was weird of course because it got to the point were I was like okay I'm gonna put on this condom are u gonna go thru with it and she was like put it on I'll do it if u do it. Well I put it on and we were both just sitting there which seemed like forever and I said well this is real creepy but are we are aren't we. And she said we shouldn't this isn't right and it's incest and I agreed and called her a chicken. Well I still had a hard on and once I called her chicken she pushed her way on top of me and sat hovering over my dick with me holding it up right at the base of her vagina. Then she looked at me while holding her breath like she was gasping and then she just sat. Well it slid in and we were both in kind of a state of shock like what the he'll just happened. At this point it was already done so she sat there for a second both of us not moving with my cock just sitting in her pussy. I said well it's already done and she shrugged her shoulders then started moving up and down slowly we both felt pleasure of course. This went on for about five minutes and I couldn't hold it anymore so as soon as she started to see me cum she slid off my cock and just had her jaw open like holy shit. Well she didn't come but we did it. She put her clothes back on as did I and we both acted like it never happened and of course never told a soul. This has only happened twice more - each time about as weird as the first. I already know it's not normal but has this ever happened to anybody else? Be honest plz.