Cousin marriage

Note: Well, I thought I'll just post up my ideas and thoughts about different/random issues.
You can pitch in if you want to!

Cousin marriage is a marriage between two cousins, in various cultures throughout history. They are particularly common in the Middle East, where in some nations they account for over half of all marriages.
- In the past, ancient Arab tribes proposed that the law of inheritance through the daughter as well as the son encouraged first-cousin marriage in order to keep wealth in the family.

I was just wondering, there are its risks but are they high? If yes, then why isn’t it banned in the Middle East and other regions? and if not then why is it banned in some countries?

What are the risks you’ll be getting yourself into if you’re married to your cousin and what diseases you may get, if any?

Here's a link to a thread I opened about this: Clicky.