I am going to guess that they were placed in th colonies as infants.
As for the FF backgrounds how hard would it have been that difficult for Cavil to infiltrate the human networks [it not networks then data bases] and plant the all of the necessary information.
We have heard many times now that, “All this has happened before and will happen again”. I think this is truly meant to be a truth in this universe. So with that in mind, I think Ellen is referring to the circle Saul & Ellen inevitably are drawn to complete with each other, time after time, life after life, cycle after cycle.