Well, not to drag things down an unrelated science tangent, but inbreeding depression affects a lot more than just undesirable recessives coming to the fore more often. There is also increased autoimmune disorders and high fetal death / failure to thrive over time, the more a population becomes inbred. Some animals (in real life, I mean) have higher tolerance for inbreeding but past a certain point it always becomes fatal to a species or strain.
