Thoughts on being attracted to people distantly related to you?

I went to a family reunion recently and I saw a cousin of mine who I don't see terribly often. She is only one year older than me (I'm 15.) The thing is she became very attractive in the time I didn't see her. Now, I'm no pervert and I knew not to say or do anything creepy/provocative, but the whole thing kind of irked me. Does anyone else have thoughts on this kind of situation? Or any stories to share?