Board Thread:Questions and Answers/@comment-44725447-20200114040022/@comment-44754903-20200115111419

I think it has something to do with their genes.I think The first Aishi was born with a Mental defect where she would not feel emotions unless she experinced Love.After she experinced love for the first time she would start feeling other emotions like Rage,Sadness ect.This defect was Genetic so it passed on to her children and so on.

(Yandere Dev says more about this in his Why yandere Chan lacks emotions Video.)