Is it normal that i'm falling in love with my step sister?

It all began a couple weeks ago. I finally met my step sister and when I saw her a special feeling came inside me. Me and her began to grow a strong relationship with each other but the past weeks things took a turn. Me and her were awake at about 12:00 at midnight. Everyone is asleep so we decide that we would go downstairs and watch T.V. We than begin to snuggle and my heart was pounding and I was so nervous. All our emotions came out from the past good and bad and that time I knew she had to be mine. She grabbed my hand as we sat through a whole comedy movie having a great time. She wrapped her arms around me and I felt like I was going to die. I don't know what came to me but I kissed her head to show some affection. She replied by giving me a kiss on the cheek. I would've died right there at the spot but I kept my cool. (May I remind you that I never had my first kiss yet.) Anyways the movies done and we go back up to my room. I felt like our hearts connected at that very moment and I had my first kiss with my step sister. It was amazing like fireworks just lighted up on the fourth of July! My question is, My heart says that I want her but is it weird that I am falling in love with my step sister?