It happens, gentile or not gentile sometimes these feelings happen and exist when two separate sexes meet each other. However don't fall for such deception or you'l end up in a mess, you have to consider what your off spring will end up and what about your family rep?..
Maybe it's because you love your cousin too much that you want to manifest it into something more however you have to consider that there are limits and boundaries scientifically that can't make it real. In Satanism we're free to to do whatever we want ( I believe Vrbz got it right just misunderstood) but we HAVE to be aware of the consequences.
The only "sin" in Satanism is ignorance.
Hail Satan!