The taboo and the forbidden at times work as strong forces that draw you towards a particular kind of behavior.
Ask yourself if your wish to date a cousin is motivated by similar reasons. If the only reason you are dating your cousin is that you like the thrill of the forbidden, then you are cheating yourself as well as being unfair to your partner.
In then end this kind of relationship based on a shallow sensation and momentary high cannot last.
The Canon law of the Roman Catholic Church in fact has annulled marriages between first cousins and banned marriages within the fourth degree of a consanguineous relationship since 1215.
And even though dispensations could be granted to get around legal barriers, they became harder to get the closer the couple are related.
You can find out more about family law in your own state by contacting a legal services office, a law school that offers legal services to students and the public, or searching your state's homepage on the internet.
You can also look it up under "marriage" or "domestic relationships" in the legal statutes for your state.
Whether you give in to such pressure or defy them would depend on how deeply you feel about your partner and whether you can support each other should your parents decide to cut you off from family resources.