Study: Marrying cousins not so risky / CNN Health PHILADELPHIA, Pennsylvania (AP) -- The risk of birth defects in children born to couples who are first or second cousins isn't as high as many experts had believed, according to a study that sheds new light on a practice that is stigmatized in many Western cultures. The study released Wednesday says married cousins are still more likely than unrelated couples to have children with a birth defect, significant mental retardation or serious genetic disease. An unrelated couple has about a 3 percent to 4 percent risk of having a child with...