[lutusp]

> The reason we reproduce sexually rather than just churning out clones of ourselves appears to be that we're more resistant to parasites/diseases if our genes keep constantly shifting into new combinations rather than hanging around for too long looking exactly the same.

That's certainly high on the list, but replacing one population with another on a regular basis is also on the list.

> This wouldn't necessarily be impacted by the parents' deliberate choice of a few specific alleles.

Of course it would. Evolution can be a complex topic, but there's one simple fact at the center -- nature knows more than we do. An organism's ability to survive, to prevail over other genotypes, speaks louder than any of our expressed tastes and choices. That means if parents make the wrong choices, nature will step in and correct them.