My sister and I were molested as kids by a babysitter. Nothing really drastic (at least with my sister, some more major stuff happened with me, a neighbor girl, and the dude babysitting us)... I think the worst was he had us hug naked while he got off. But this was all presented to us as "playing doctor"... Innocent and all, right?
Well fast forward until we were both in our early teens and puberty kicked in, and our parents gave us this cartoonish book "Where Did I Come From?" about sex. This happened about the same time that internet porn became a thing, and I found out about it. Hey... wow. The stuff in this book sounds pretty cool! And hey check out this stuff I found on the computer! Hey sis, would you ever want to try this? It sounds like those games we used to play!
And next thing you know, we're "playing doctor" again, only this time what starts as naked hugging becomes oral sex and fingering within a few months. And this goes on for about 2 years. At some point it's hard to justify that it's some childish game when you're hoping your weed dealer doesn't show up while your sister is riding your face. Finally, we decided to try to fuck. We put down a towel in case her cherry popped, but were too stupid to use a condom. Fortunately, we were also too stupid to figure out how to get a dick more than halfway into a girl... it isn't as easy as it looks in porn. After an hour or so, we gave up. We tried again the next week with just as much fail.
In between the two times we tried to fuck, I went to my college library and was looking at sex books, hoping to find hot shit. Instead I found out there was this thing called "incest" and that it was like, evil and wrong blah blah blah... and holy crap that's what I'd been doing for a couple years! After the second time I tried and failed to fuck my sister, I was like... shit... this is probably not a good idea.
So, I cut it off. My sister came and tried to initiate "playing doctor" (kind of a joke after sticking my dick half way into her twice) a few times and I pretended to be busy with homework or other shit. After like 2 months that ended.
A year or so after that we talked, and I asked what she thought... she said "we were too young."
That was that until about 7 or 8 years later when she told me and our parents about everything... The ultimate truth of it though is that to her, we had a thing going, and the fucking we were doing while not romantic in her eyes (or mine, to me it was just for fun) was a sibling bonding thing and when I cut it off without any explanation (I didn't want to tell her what we were doing was "evil") I basically was rejecting her.
So... if you want to fuck your sister, and she's interested in fucking you, all I can say is be sure you both talk about it before hand and want the same thing.
