I tried with two of my cousins both turned me down they both have thick long cocks at least I saw them

If all involved are consenting ADULTS, and BC methods are used, then it can be an enjoyable and close experience.

Vice is nice
But incest is best
As long as no force is used, keep it in the family

The fact that this topic is even being raised is disturbing, and I am even more chagrined by the cavalier attitude expressed in the replies.
The word derives from Latin word "incestus" meaning unchaster or impure. With that said, no where in history has the practice ever been accepted. It has always been frowned upon and laws have been structured against it.
It still takes place, unfortunately. Participants can be parent/child or between siblings. In most cases some type of coercion is employed, either the promise of reward or the threat/usage of violence. In any case it violates the inherent expectation of trust between family members. Victims can end up with severe psychological issues from the experience, such as the inability to have intimacy or trust in their spouse or partner, along with a whole laundry list of other problems.
It's aberrant behavior any way you look at it, and if it's something you find attractive or acceptable, you have some serious problems going on within yourself.

That is a rotten question. I was a victim of INCEST....sure, lots of fun there. 20 years to work through the garbage it left me with.

It's worth remembering that incest is frowned upon (and illegal in most countries) for good reason. I was once told a story about two villages in a rural part of England where incest was actually extremely common and went back into the mists of time. In the years between the two world wars, one of the local doctors went around the villages knocking on doors and telling the men that sex with their sisters was what was causing the awful deformities in many of the children that resulted. Apparently, the inhabitants of one village had almost entirely become deformed with protruding lower jaws, and the other had severe mental problems.

On a positive note about incest. My sister would jerk me off a lot when we where young. We would shower together and she would play with my cock and make me come. She also let me play with her milky tits and breast feeded me some years later. She was the first girl I seen pee.