The state has a legitimate interest in protecting the welfare of children, and any children conceived in an incestuous relationship are at an elevated risk of having both major birth defects and other subtler physical defects. That by itself ought to be enough to maintain a ban on incestuous relationships.
The law, according to lawrence, does not consider mere breeding. (even according to the ABA's model divorce code, adult activity defines the relations NOT the mere accessory of producing offspring)
Thus, according to the left SEX for recreation is all that matters.
"The state has a legitimate interest in protecting the welfare of children, and any children conceived in an incestuous relationship are at an elevated risk of having both major birth defects and other subtler physical defects."
What about when one of them is infertile? Or when they're of the same sex?
And what about people with genetic diseases that have children ? They're not put in prison even though their children have a higher risk of getting the same genetic disease.
(Denny Crane: "Sometimes you can only look for answers from God and failing that... and Fox News".)
This statement is only valid if the parents (or their parents) are also the product of incest..
The only other contributing factor would be if there were specifically identifiable genetic or physiological defects that had been passed down to the parents / grandparents that could be passed to the offspring..
In other words, it has to be more than a "singular" occurance within a familial group, it has to be an accepted practice..
The taboo against incest requires more than one generation.. then and only then is it valid..
This couple's children stand about the same prospect of birth defects or other physical defect as anyone else..
The same is true of children whose parents are both Ashkenazi Jews.
You really want to go down that road?