>>544743328
Well, for something like Cystic Fibrosis which among my genetic heritage (white western european, specifically English, Irish, and Scottish ethnic groups) has a carrier rate of roughly 1 in 25. Under normal circumstances the chances of two randomly-selected people from this population group producing a child with Cystic Fibrosis is .04% or 1/2500 children. By comparison, a brother-sister couple (also randomly selected from this population) is 6.25x more likely to produce a child with Cystic Fibrosis, which amounts to a whopping... 0.25% chance. For reference, you're slightly more than four times as likely to die in a car crash over the course of your lifetime in America than you are to produce a defective baby with your sisterwife.
Anyway, thanks for playing.