I can't stop crushing on my older sister.

I'm a 16 year old and my sister is 21 years old. She is very beautiful, with long, dark hair, a golden girl tan and a pretty smile. When she's home, she always wears a black tank top and leggings, and I feel attracted to her, and I can't stop looking at her. She is always a good girl and very nice to me, and I know she loves me and I know I love her, but I can't stop having these feelings. I just want us to be very close, I don't know if that's wrong.