Cousin Marriage - A new group is struggling for acceptance. The group is people who are married to their cousins. These people note that 20 percent of marriages around the world are between first cousins. Now a study by the National Society of Genetic Counselors says that having a child with your first cousin raises the risk of a significant birth defect from about 3-to-4 percent to about 4-to-7 percent. The above article provides some more information about first cousin marriage.