User blog comment:Nick D Wolfwood/Hell, where naughty Death Gods go????/@comment-1961713-20100601190703

I think the Noble Houses simply 'reproduce' and 'adopts' as in Rukia's case with the Kuchiki's House. Or would you refer New Captain Amagai Arc - where Rurichiyo Kasumioji was indeed born into this clan Kasumioji who according to Yoruichi was only below from the 4 great noble families (others may deemed unreliable because it only appears in anime)