But Brian's father, Dennis, knew their options were limited. "We said, 'Well, we've got a couple of choices. Either we can say no, we don't want this to happen' -- which, you know it wasn't our choice if this is what they were going to do. They're both over 21. I said, hey, we're not gonna lose you."

The parents blessed the marriage. Then Caren and Brian decided to have kids. They'd heard stories about birth defects and worried that their kids would be stupid. But they had kids anyway -- two sons -- each of whom went on to be at the top of his class in school.

That confounds the conventional wisdom. Novels like James Dickey's "Deliverance" and movies like "Brighton Beach Memoirs" reinforce the notion that cousin marriage will produce retarded children. ("You'll have a baby with nine heads!") But a study funded by the National Society of Genetic Counselors revealed that assumptions about cousin marriage are unfounded. The risks of birth defects or mental retardation are 2 or 3 percent higher among married cousins, but other parental risk factors are higher. Age, for example, increases the risk much more: There's a 6 to 8 percent chance that a woman over 40 will give birth to a child with birth defects.

It would be ridiculous, however, to prohibit middle-aged women from having children. It's equally wrong to prohibit cousins from marrying. There are risks and challenges in any marriage, but it should not be for politicians to decide such intimate matters as whether you get to marry the person you love. Love, marriage and procreation are personal choices better not left to "experts" who are often repeating myths.

There is one real risk, however, to cousin marriage. Pat Bradfield, Caren Wagner's mother, had a warning about divorce: "You could divorce your husband," she told Caren, "but you can't divorce the whole family. Your father-in-law and your mother-in-law would still be your uncle and aunt."

Now that's expert advice worth considering.