I think it’s actually hypocritical to not allow an incestuous marriage. Plaintiffs in Obergefell v. Hodges based most of their arguments on the idea that marriage is about love, not children. The argument against siblings or first cousins marrying is really because it’s a taboo. Yes, a straight couple could have a child with serious defects but lots of other, unrelated people, also have genes that would create a child with serious defects.
The one-off cousin baby has relatively low chances of genetic problems, it’s near the background rate. It’s only when you have multiple generations of in-breeding that you start to get problems. But, it’s pretty tough to draw the line at “don’t marry your cousin too often.”
I think it’s actually hypocritical to not allow an incestuous marriage. Plaintiffs in Obergefell v. Hodges based most of their arguments on the idea that marriage is about love, not children. The argument against siblings or first cousins marrying is really because it’s a taboo. Yes, a straight couple could have a child with serious defects but lots of other, unrelated people, also have genes that would create a child with serious defects.
The one-off cousin baby has relatively low chances of genetic problems, it’s near the background rate. It’s only when you have multiple generations of in-breeding that you start to get problems. But, it’s pretty tough to draw the line at “don’t marry your cousin too often.”