Inbreeding

[eyesOpened]

I'm bringing a question which arose on a different (non-science) forum. The question arose like this (paraphrasing):
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A: Inbreeding is unethical because of the high chances of birth defects. Birth defects are caused by similar genes. If you keep a gene that may cause a birth defect in one family, there are no other genes to dillute the birth defect gene.
B: What's to say that similar genes won't just as likely cause "birth enhancements", where "enhancement" means the opposite of "defect"?
A: Most of the odd things tied to recessive genes in humans are defects.
B: What basis is there for that assertion?
A: Science.
B: Has this alleged "science" ever been published, and if so, where specifically can it be read?
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What do you all think?

[Darby]

There are a couple of simple reasons why your scenario doesn't work -

A genetic change that affects the coded protein (most changes are pretty neutral) is more likely to harm its effectiveness than enhance it. Such changed alleles are recessive, covered up when paired with codes that still produce good working proteins, and random, but passing down a family line. Inbreeding can put together 2 bad recessives - that's why it's bad.

A mutation that enhances protein function would probably not be recessive, since the enhanced protein would produce enhanced effects - there's no reason to expect the "regular" proteins to hide the enhancement.