I think it's from associating sex with rituals. Before puberty I would watch a lot of horror shows, and a lot of them involved, witch or magicians capturing women, turning them into stones ,doll, frozen in ice or ritualistic sacrifices to gain eternal youth etc. So after hitting puberty, i would fantasize about that sort of stuffs.
I was also religious, so seeing ritualistic sacrifices in public during Eid and hearing the story of Ibrahim(Abraham) attempting to sacrifice his son probably got me into Dolcett fantasy.