It's wrong to be intimate with your cousin.
Brad's female cousin keeps hitting on him, and he thinks she is attractive.
Brad has to decide whether to have sex with his cousin.
Brad doesn't want inbred kids, so he decides not to have sex with his cousin.
Brad can't resist his cousin and decides to have sex with her.
Brad feels good about himself and knows he can resist temptation.
Brad ends up feeling ashamed and has trouble getting rid of the memory.