From another article about the science of genetic problems with cousin marriage here.
Cousin marriage is also legal in over half the states...because--even though unpleasant to consider--there is no scientific evidence marriage to even first-cousins produces undue numbers of birth defects--as their genetic consanguinity is far enough away.
Marrying half (or full!) siblings yes, like the Pharaohs, will guarantee birth defects....which is why the Bible forbids it. The Bible however, does NOT forbid marrying cousins, therefore morally, it is NOT incest.
There are a lot of reasons why Muslim peoples are backward, but cousin marriage isn't one of them. Do they marry half brothers or sisters? If so, then yes, that is a problem. This report is rubbish.
The Love That Dare Not Speak Its Surname
What's wrong with marrying your cousin?
By William SaletanPosted Wednesday, April 10, 2002, at 5:32 PM ETIllustration by Robert NeubeckerA 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, that Albert Einstein and Charles Darwin married their first cousins, and that first-cousin marriage, while prohibited in half the United States, is legal in Canada and throughout Europe. 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. According to the authors, that difference isn't big enough to justify genetic testing of cousin couples, much less bans on cousin marriage. From this, the media have concluded that marrying your first cousin is "OK." Is it?
From another article about the science of genetic problems with cousin marriage here.