Why do children whose mother and father are siblings result in genetic disabilities?
This is indeed more common when closely related family members produce offspring. This is as a result of the fact that most genetic diseases are recessive, which means that two identical recessive copies are required to result in a disease in offspring. Family members (that are heterozygous for the disease) may have inherited the same defective copy making it more likely for the offspring to inherit the disease.
Answered By: Dr. Gijs Van Rooijen