[curmudgeonII]

That rarely brings out anything but bad.

You may, however, think of a couple of items which counter your argument:
1. Abraham and Sarah [founders of the Jewish race] were half brother and sister.
2. There were, apparently, a large number of brother-sister and father-daughter incestuous activities among the Egyptian pharoahs with little discernable adverse reaction.

Please don't take these points as an argument in favor of incest. I find the whole idea repulsive. But the potential genetic results of incest are usually extremely exagerated to a point of being, scientifically, ridiculous. [Just read some of the earlier replies in this post.]

[jwalsh07]

There were, apparently, a large number of brother-sister and father-daughter incestuous activities among the Egyptian pharoahs with little discernable adverse reaction.

Easy for you to say, you weren't the 8 year old daughter with the Egyptian pervert hounding you every night.

[cavtrooper21]

There is a factor that you have overlooked when you speak of the Pharaohs.
Many were found to have multiple physical disorders and defects that have direct connections to inbreeding and incest, and who's to say that much of their "god-like" behavior was brought about by genetically linked mental instability.
King Tut was found to have skeletal defects related to inbreeding, and his father, who's name escapes me, was also said to have been "misshapen".
These are extreme, involving multi-generational crossing and recrossing of the same narrow bloodlines.
I feel the same way you do about incest.. It's wrong, and I see no reason to let it start just because some "progressive" thinks it's OK.