Is it wrong that I'm attracted to my cousin?
Yes, that seems inappropriate. What is it that makes you attracted to your cousin?
Because in my planet incest is normal.
Well here on earth, that is not okay. You should not be attracted to any of your family members like that.
But it is natural.
While attraction is normal, it is not normal to be physically attracted to a family member. It would be best for you to recognize the flaw in this thought and change the way you see your cousin.