@Drifter That doesn't sound far off tbh. She did ask the gyaru if he did any experiments on her so I wouldn't be surprised if Fia was born from Bertha's DNA.
@Drifter & @Tsolux: Er, you guys do remember that the only stated ingredient of human origin that's used in the creation of a homunculus in this setting is semen, right? Far more likely that she's based on his genome instead.