Board Thread:Warhammer 40k General Discussion/@comment-17722292-20130905160315/@comment-7123746-20130909161526

From the standpoint of what genetic diversity means to us, you're absolutely right. I think though, they might be referring more to not putting all their gene seed in one basket, so to speak. When they lost Caliban they probably became very wary of putting all their stock into one world again.

If your recruiting base comes from many worlds, a rebellion of one world out of a hundred isn't quite the disaster that having your only recruiting world rebel would be.