Get aroused with my cousin

i often massage my girl cousin. My problem is, sometimes im being carried on by what i am doing that i can nearly touch her private parts and get aroused, thinking that i can touch her anywhere and she's not complaining or anything. (its like she's just letting me go wherever i want to.) I can feel my heartbeat rises and i know she feels it too. Maybe because she knows im her cousin and nothing can happen between us. OR maybe she's liking it too! What do you guys think? Is it normal to feel this way, especially with your cousin? How will i know if she's liking it too or not?

PS: she has a nice body, bust, and breasts.