Like her mentor, EGON SPENGLER, the KYLIE GRIFFIN of DIMENSION 68-E was affected by the supernatural at a young age. She was targeted by THE GRUNDEL, a parasitic entity that preys on, corrupts and transforms children into its own image.
Kylie was able to resist the Grundel's attempts at corrupting her, but her friend JACK wasn't so lucky -- he was turned into a grundel himself.
This was the key event that drove Kylie's interest in studying parapsychology and being the best GHOSTBUSTER she could be. She's brave, but not fearless -- to this day, she has nightmares about the loss of her friend.