Incest is a redneck/jew/Muslim pastime and an Anime plot device in which two people who are thoroughly related engage in sexual intercourse. As to why anyone would ever try this knowing that it usually results with hairless, toothless, retarded babies that play the banjo is due to them knowing that their own ugly-ass family members are the only ones who will give them a shot at sex. Along with rape, pedophilia and hermaphrodites, Incest is one of the few things that theporn-desensitized still get off to.
