Natural Body Magic is a fetish/interest for people who can detach parts without blood lose or injury and still control the parts, even in cases were the head is detached. This fetish is thought to be male dominated, but looking back at history, it's clear to see that there's only more male fetish artist. There's a reason why "La Guillotine" is feminine in french; most of the people who watched the beheadings were women.
The girl was very interested in taking her dolls apart and playing with the parts. She was also very interested with the story of Sleepy Hollow and would spend hours obsessing over it. Due to this, she developed a detachment fetish, otherwise known as NBM (natural body magic)