I am in love with my sister!
So, me and my sister, both aged 18 (twins) live together in an apartment. We were watching a film together, and cuddling, and suddenly I got an erection. The next week, I peeked at her washing herself, and she looked so hot, I watched for ages. Then just the other day, she said she couldn't sleep, so she came into my room. We talked for a while, and then she approached me. She climbed on to my bed and pressed herself on me. We kissed passionately for ages, then she took her clothes off. She looked so stunning, her breasts were big and amazing, and her vagina looked beautiful. I fucked her and it felt so wonderful and right. We woke up the next morning and she smiled at me. We've been having sex ever since, she is the most beautiful girl I know and and it seems so normal. But is it?