Is it normal with sister?

Okay. Well my sister is 17 and so am I...we are twins. (I'm a guy) She was taking a bath one day and the door was open a little so I peeked in. She was laying back with her big boobs up and her sweet looking vagina floating on the surface. My hard on went thru my boxers and I was stroking it. She started fingering herself. And I jizzed on my hand. That night while she was asleep I crept into her room. She wore a thong and nothing else, her big boobs hanging out. My hard on was so hard! I slipped her thong down and licked her pussy. And then I jizzed all over her huge boobs. She woke up and gave my a hand job. And then I fucked her hard ( with a condom). When she fell back asleep, I first put my dick in her mouth. Then I gave her hard core anal. In the morning when I was taking a shower, she came in and sucked my dick and put it up her pussy. It was so hot. But she wasn't having her period then so I was good. Then gave her more anal. It has become pretty regular now and we have bought our own place. IIN?