Most of us don't consider it negligence when genetically-distant partners have biological children, even when there is a high risk of passing genetic "abnormalities". Neither do most of us consider it negligence when parents have children in terrible conditions.
So considering that the biological children born as a result of GSA relationships only have a slightly higher risk of inheriting genetic "abnormalities", we are in no position to outlaw procreation amongst GSA-couples.
It is not considered negligence for distantly related partners to have children, even if their is a high risk of passing genetic "defects". It is not considered negligence for parents to have children in terrible living conditions.
Therefore, it is not negligence for GSA-partners to have (biological) children of their own, especially considering that the average risk of inheriting genetic "defects" only increases slightly for children born of such relationships.
And how do you who believe they shouldn't propose we tell the difference between true love and "genetic sexual attraction"? That's right, you can't. So of course they should be allowed to procreate. And even if there's ever a test to show the difference, I still don't think it should happen.
I know healthy, bright, adorable children born to people brought together through GSA. We let people with obvious, serious, genetic diseases date, have sex, marry, and have children (and do any of those without the others). Under the principles of equality and reproductive rights, there is no rational reason to deny these rights to people brought together via GSA, as most children born to close relatives are healthy.
While I am not against people being together who genuinely care for each other and have an attraction (while I would never do that myself), I do believe that genetic sexually active couples should take measures as to not get pregnant. You do not want to bring a child into this world who would have birth defects.
Let's call genetic sexual attraction for what it really is--incest. People who act on that impulse should never procreate because it can cause genetic deformities. Two people who are too similar genetically cause congenital defects. The French royal family did that in the 1600s and 1700s which led to all sorts of genetic abnormalities. For the same reason, purebred cats and dogs also have genetic defects specific to certain breeds.
Acting on genetic sexual attraction is just wrong. Perhaps not biologically, but definitely in the context of the social world we live in . The stigma that accompanies it is damaging to everyone involved. Very few people find it socially acceptable and you would be enduring harsh criticism from almost everyone. No amount of attraction is worth the lifelong disabling social factors that will accompany it.
Genetic sexual attraction was studied under the basis of adoption where potentially "lost" family members could be potentially attracted to each other when meeting in adulthood for the first time due to adoption into other families. Therefore, it really has little to do with the masses, but only those involved in very special circumstances. Incest, obviously doesn't promote healthy off-spring, so clearly procreating based on genetic attraction in this specific area of study is not a good idea.