Should incest between consenting adults be a crime?

[Angrboda]

Here's something I found that is relevant.

Because of the potential risks, couples that are closely related are often advised to see a genetic counselor. The genetic counselor can figure out if they are both carriers of a disease. And then the couple can weigh the risks.

If siblings that want to have sex see a genetic counselor and confirm that they are not going to pass on any recessive diseases, is it then okay? A related question. We generally consider it ethically questionable to abort a late term fetus because of abnormalities, and many children with birth defects are raised by parents who are happy to have them. These children don't necessarily have terrible lives. Who are we to say that having sex that may result in a child with long term challenges to its survival is wrong? We don't euthanize such children. Should we?