Originally Posted by nwshc
Why would the bad genes get flushed out? They would always stay in you somewhere. If your great great " " " " grandpa had dandruff, even if everyone else up to you didnt, you still could have dandruff. It just stays hiding withing you.
Easy. If incest leads to defects half of the time, the other half won't be defected. If the defected don't reproduce with each other, and the non-defected do, the non-defected's children will have a lower chance of being defected. Repeat this for a few generations and you'll have less defects in the family overall.