Incestous relationships

Some time ago I read a very appealing article about marriages between cousins in some Asian countries. It appears that this phenomenon is becoming more and more common in Europe because of Asian emigrants living for instance in Great Britain and in Scandinavian countries.
I've found out that in the view of the Koran, Muslim people can't marry their parents or their siblings BUT they can marry their own cousins! I find it truly shocking but for these people it's nothing extraordinary. It's their culture.
According to some research, many children, who are born this way, have plenty of health issues or are disabled. 30% of British children, who suffer from genetical diseases, are from Pakistani families and around 70% of Pakistani people marry their cousins!
What do you think about this kind of relationships??