04-13-2024, 05:50 PM
Ted King wrote:
https://www.nytimes.com/2002/04/04/us/fe...usins.html
First cousins are somewhat more likely than unrelated parents to have a child with a serious birth defect, mental retardation or genetic disease, but their increased risk is nowhere near as large as most people think, the scientists said.
In the general population, the risk that a child will be born with a serious problem like spina bifida or cystic fibrosis is 3 percent to 4 percent; to that background risk, first cousins must add another 1.7 to 2.8 percentage points, the report said.
Is a couple of percent enough risk to discourage first cousins from having children? I don't think there is an objective way to determine that. I think it is worth making sure the first cousins are aware of the amount of risk but I think the risk is low enough that I would leave it to them to decide.
So would that mean, statistically, that for every 100 "first cousin" parent couples there would be 5 to 7 whose children would have birth defects that were the result of their genetic relationship?