Almost My Point Exactly
Sage, I agree with you with one exception. It is only with many repetitive generations of inbreading that genetic problems occur. A single instance of incest resulting in offspring, even by closely related individuals like siblings or parent and child, very rarely results in any type of increased risk of a physical defect.
If you look at aristocratic families or royalty, where close inbreeding has taken place for generations or even hundreds or thousands of years, genetic abberations rarely manifest themselves.
Also, it is a commonly known fact that physical characteristics tend to skip generations. That alone could be an indication that our genetic makeup has made an allowance for offspring of closely related individuals.
By that I mean, individuals of the same generation would not have the same dominant defective marker in their genetic makeup. Also, individuals of differing generations would have a recessive marker for the same defective gene. Hence, very rarely would such a genetic defect marker become dominant and manifest itself in a physical defect in the offspring of very closely related individuals.
Yes I understand that there are some dominant defective genetic markers that always show up in EVERY GENERATION, like hemophelia or color blindness. But because those defects show up in every generation of offspring of all carriers of the defective gene, those types of defects must be excluded.
Incest has been part of our species since time began and I believe it will continue to be a part of it forever. As I have said before, incest is a natural progression of the expression of love between closely related individuals. The keyword here is Natural.