Responses
Latest chapter dropped more hints. They are siblings. Looks like the temple doesn't turn just any human into a divine beast. They have been abducting all the children of this particular noble family (except for the eldest child) for generations. Looks like most if not all the "divine beasts" are actually the FL's family. (╯°Д °)╯╧╧
And we got more info. Divine beast my foot. They are beastman who lost their ability the shift. The temple figured out how to trap them in their beast form. They naturally absorb mana to regain their normal state.
Wait don't tell me they're siblings?? So the experiment being conducted in the temple was turning humans into divine beasts??