Perhaps the answer was there from the beginning, and I didn't realize it.
Why are the members treated as having a "unique characteristic" due to their innate bodies?
If they were just ordinary humans born with a different appearance, Wonderstein's bio-manipulation abilities should have worked on them.
However, the system viewed their heterogeneous bodies as a "characteristic."
The meaning behind this was clear.
The fact that the members were born as monsters was due to Debulroots.
Therefore, their physical features were treated as a "characteristic."
Debulroots from their parents' bodies passed on to them during their fetal stages.
They were in a state where genes were already combined with Debulroots from the beginning of the formation of their bodies.
That's why even with the power of a bio-mancer, their bodies could not be altered.
All of this raised one more question for me.
Why did Wonderstein gather them?