>> It increases genetic diversity in the pool of offspring. That diversity could then raise the fitness of future generations by making them stronger, faster,

>> It increases genetic diversity in the pool of offspring. That diversity could then raise the fitness of future generations by making them stronger, faster, more resistant to parasites or otherwise more adaptable Probably off topic, but I didn't know this was not a commonly accepted explanation. When I went to school (maybe middle school) in Vietnam in the early 90s, I was taught this. My biology teacher said this explains why marriage between closed relatives is not recommended because it leads to less diversity, and a bad gene would have chance to manifest.