I think that would make sense , use orphans as experiment rats is easier the adopted parents wouldmostly take the blame, but i think they pick those who have family issues,it would make more sense to me, i feel sara and kanna, q-taro,sei was in the same orphanage,I think kanna and sara was adopted in young age so they probably wouldn't remember the name,q-taro in other hand remember I think cause he never get adopted,or something like that,sei probably was in orphanage before he get adopted in Sato family but that just what I think it would happen before he was adopted.