Should incest between consenting adults be a crime?

[AFTT47]

There is an evolutionary reason we don't fuck family members closely genetically related. It is still a "EWE" factor for most humans. 

This may be true, but should it be illegal when there is no possibility of children, such as when the man has had a vasectomy, or the woman infertile?  What if they are practicing responsible birth control?  Is the "ewe" factor alone enough to justify discouraging or criminalizing otherwise harmless, consensual conduct?

I take it you're referring to the potential for genetically handicapped children to be born.  I'll note two things.  First, my understanding is that the risk is exaggerated.  Second, if we forbid sex for that reason, do we also forbid sex among others who might be promoting genetic abnormalities by having sex, such as parents who both carry the Tay Sachs gene?  Once we go down that road, do we allow other justifications for denying people the right to have sex and have children because the consequences in terms of the children's well-being or quality of life are likely to be undesirable?  Do we forbid mothers of down syndrome babies to have sex?  (I don't offhand know if there is an increased risk for such mothers, but I think you know the type of thing that I mean.)  Do we extend such reasons to whether the parents are unintelligent?  Do we forbid black people from having sex because a black child is more likely to have a lower quality of life than a white child?

You beat me to answering your own poll question. Definitely, "No."

As you said, the dangers of genetic problems in a single generation are small. Those dangers multiply with subsequent generations so there WILL be problems if incest were part of a family tradition. That "EWE factor" that Brian mentioned is very strong though and seems to be plenty enough from discouraging incest in amounts where it will be a problem.

I have personally seen problems related to inbreeding. I lived on the Pacific island of Guam for 6 years. The island has a population of about 150,000 with about 40% being the native Guam people, the Chamoru. They tend to stick to their own as far as partners go. In the past, before the age of automobiles, they tended to stick to their own village. As a result, diabetes and various heart ailments are rampant there. I think that sort of situation is far more of a threat than incest will ever be.