Marry someone born to consanguineous couple?

[anotheruser2223]

Hello,

I am dating someone who was born to a consanguineous couple (his father married his niece). I am completely unrelated to him. If we get married, will our children have elevated risks for any birth defects because of his parents' consanguinity?

Also, note that he had a younger brother who passed away. He had a mental disease since birth.

[Ferrum]

I think it would be a small , very small likelihood of that . Not impossible , but most likely unlikely .