..."Americans just don't understand what a different world Iraq is because of these highly unusual cousin marriages," said Robin Fox of Rutgers University, the author of "Kinship and Marriage," a widely used anthropology textbook. "Liberal democracy is based on the Western idea of autonomous individuals committed to a public good, but that's not how members of these tight and bounded kin groups see the world. Their world is divided into two groups: kin and strangers."

Iraqis frequently describe nepotism not as a civic problem but as a moral duty. The notion that Iraq's next leader would put public service ahead of family obligations drew a smile from Iqbal's uncle and father-in-law, Sheik Yousif Sayel, the patriarch in charge of the clan's farm on the Tigris River south of Baghdad.

"In this country, whoever is in power will bring his relatives in from the village and give them important positions," Sheik Yousif said, sitting in the garden surrounded by some of his 21 children and 83 grandchildren. "That is what Saddam did, and now those relatives are fulfilling their obligation to protect him from the Americans."

Saddam Hussein married a first cousin who grew up in the same house as he did, and he ordered most of his children to marry their cousins. Sheik Yousif said he never forced any of his children to marry anyone, but more than half of the ones to marry have wed cousins. The patriarch was often the one who first suggested the match, as he did with his son Muhammad nine years ago...

..."I told my children not to participate in any outside groups or clubs," Sheik Yousif said. "We don't want distractions. We have a dynasty to preserve." To make his point, he told his sons to unroll the family tree, a scroll 70 feet long with lots of cousins intertwined in the branches.

Cousin marriage was once the norm throughout the world, but it became taboo in Europe after a long campaign by the Roman Catholic Church. Theologians like St. Augustine and St. Thomas argued that the practice promoted family loyalties at the expense of universal love and social harmony. Eliminating it was seen as a way to reduce clan warfare and promote loyalty to larger social institutions — like the church.

The practice became rare in the West, especially after evidence emerged of genetic risks to offspring, but it has persisted in some places, notably the Middle East, which is exceptional because of both the high prevalence and the restrictive form it takes. In other societies, a woman typically weds a cousin outside her social group, like a maternal cousin living in a clan led by a different patriarch. But in Iraq the ideal is for the woman to remain within the clan by marrying the son of her father's brother, as Iqbal did.

The families resulting from these marriages have made nation-building a frustrating process in the Middle East, as King Faisal and T. E. Lawrence both complained after efforts to unite Arab tribes.

"The tribes were convinced that they had made a free and Arab Government, and that each of them was It," Lawrence wrote in "Seven Pillars of Wisdom" in 1926. "They were independent and would enjoy themselves a conviction and resolution which might have led to anarchy, if they had not made more stringent the family tie, and the bonds of kin-responsibility. But this entailed a negation of central power."...