It's exactly the same thing. People overblow the chances of deformation. You only get truly negative results when several generations of incest are stacked back to back, I.E. royalty. People like to coin phrases like "Your child is TWICE as likely to have a defect in such relationships!"..and that's true. It rises from 2% to a whipping, groundbreaking 3.5%, which is also a risk you take by having children in your late 30's. You have no other reason to disagree with the practice.