...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 such problems. But for close...

...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 such problems. But for close...

...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 such problems. But for close...