Marriage between cousins is restricted or regulated in the United States to help prevent birth defects and genetic disorders in children.Birth defects are more common among children born to members of the same family.

Third cousins usually share a set of great-great-grandparents and one-eighth of the genetic pool.

However, your child will only have one-half of your genetic pool and would only share one-sixteenth of the genetic pool with your third cousin. Many people who grow up in the same area probably have this much connection with their spouses and do not even know it.

Now, there may be other reasons that this arrangement is bad.

I would certainly be very uncomfortable with a first cousin arrangement since this would be very close to the biblical prohibition.

The fuller prohibition has come partly from a desire to keep as far as possible away from something that is spoken of with such serious warning in scripture. As our society has become more numerous and diverse, it has become more repulsive to us to marry close to family. Cousins usually share a common set of grandparents (though it can be only one grandparent) and one-half of the genetic pool.

It has also become a joke to put down those who were considered to be from the sticks--that is, rural folks who did not know any better. Second cousins usually share a common set of great-grandparents and one-fourth of the genetic pool.And if a man shall take his sister, his father's daughter, or his mother's daughter, and see her nakedness, and she see his nakedness; it is a wicked thing; and they shall be cut off in the sight of their people: he hath uncovered his sister's nakedness; he shall bear his iniquity. They include father, mother, step-mother, sister, step-sister, grandchildren, aunt, uncle, daughter in law, and sister in law.Technically, this does not prohibit marriage to cousins.There is no scientific grounding for it." In the UK, the issue came to the fore when the MP Phil Woolas, now the Immigration minister, claimed earlier this year that first-cousin marriages within Asian communities in Britain resulted in an increasing number of children with health problems."A lot of arranged marriages are with first cousins, and that produces lots of genetic problems in terms of disability [in children]," Mr Woolas said.Khalid Mahmood The Birmingham MP married his first cousin, Rifat, when he was in his twenties.