Somewhere I ran across a really interesting article on "Wright's Inbreeding Coefficient", a measure of frequency of allozygous genes (not only homozygous, but same copy). One really interesting piece of information was that the worst possible inbreeding you can perform is parent to offspring, and that sib-sib trails significantly behind this, followed by half-sib pairings. Just something to keep in mind IF you are watching out for the genetic diversity.

JonV