Is it not possible that the midichlorians are inherent within some of the various species in the galaxy, but on occasion, the midichlorian count is "high" in some offspring, and if that child shows some force sensitivisy, they ship them off to Jedi camp?
I'd assume that would be the case. Not the Jedi being an exclusive midichlorian breeding pool. heh
Maybe the point is the Jedi Council FEARS Jedi breeding, which could end up making a SUPAR JEDI that quite possibly could be a really bad thing?