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Early humans were genetically perfect, thus inbreeding was a good thing for them. Had they not bred, we would not be here.
Later, sin took its toll, IQs dropped, defects appeared.
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2.5 million years ago?
“Early humans were genetically perfect, thus inbreeding was a good thing for them.”
Would only take a few generations for imperfections to crop up, however—which is why law against incest was written. It is notable though, there there were no laws on incest until Moses, about 1,500 BC. Abraham himself married his half-sister.
It is also interesting that Abraham’s nephew, Lot, was condemned....for sex with his own daughters (giving rise to the Moabite & Amonite nations)—so certain forms of incest were known as wrong (at least parent/child incest).