German incest couple lose European Court case

[Clouseau2]

43. Much higher than that

First cousins are doubled already:

CNN article

According to the recent report, children of unrelated parents have a 3 percent to 4 percent chance of being born with a serious birth defect. Children of first cousins have only a slighter higher risk--roughly a 4 percent to 7 percent chance.


In a Salon.com article the 50% rate is mentioned:

Salon.com article

Among offspring of siblings, there's a 50 percent chance of disability, and so far the German couple's children have proved the rule: According to Steubing, one son has "epilepsy and learning difficulties" and one daughter has "special needs."


I admit I could not find any studies quoting this number, I only saw one that claimed 7-31% which is too big a range to have any real meaning.