What is Genetics? : Frequent Questions & Answers

If cousins get married, are they at risk of having children with genetic conditions?

Any couple related or not, also is at risk of having a child with genetic conditions or health problems! Although taboo in some cultures, marriage between first cousins is accepted in many cultures around the world. The vast majority of children of first cousins are healthy and do not have problems due to their parents’ relatedness. It is important to keep in mind that even for an unrelated couple, there is an approximately 2-3% chance that their child is born with a birth defect, genetic syndrome, or disability.

The risk for children of first cousins is increased over this background, by about 3%. The risk for genetic conditions and health problems does increase as the relatedness of parents increases. For example, marriages between brothers and sisters are not typically culturally accepted. This is likely due to the dramatic increase in birth defects, genetic conditions and health problems seen in children of these matings.