I have no idea--the way the game phrased it, it made it sound like Hollander didn't start work on making Angeal until after discovering Gen was a flop, and that had to be soon after birth or immediately before, since Gen, Seph, and Angeal are all "around 25" when CC happens--so all three have to be in the 24-26 range. And in order for Gen to just have a feeling he wasn't their kid but not know for sure, he had to be under 3 or 4 to have been given to the Rhapsodoses, and I'd say even that old would be seriously pushing it.