http://www.slate.com/blogs/blogs/humannature/archive/2008/04/16/incest-in-nature.aspxSix years ago, I wrote about the science and ethics of incest (" The Love That Dare Not Speak Its Surname "). At the time, a study showed that having a child with your first cousin raised the risk of a significant birth defect from about 3-to-4 percentenCommunityServer 2.1 SP2 (Build: 61129.2)