If I am not attracted to this boy why am I acting like this?

There's a new guy who has started coming into my work, he's 18 (I'm 17) and has just moved over from Ireland to get sorted for when he starts University (I've known his older brother for quite a while through work) well anyway the first time I saw this guy I kept catching him looking at me, he was joking with me about being lazy in work and eventually we started to flirt (I am a naturally flirty person) This is now are regular routine when we see each other but the thing is I dont feel I am attracted to this guy even though I am not attracted to him I tend to ask mutual friends about him and continue to flirt with him whenever we see each other. I am really unsure about what I am feeling for this guy if I am not attracted to him.