Question regarding the legs of victims

Do all the daughters have weirdly long legs? A thing that has struck me since the beginning is that victims have weirdly longlegs. I know there’s a cuckoo demon child theory going around. Could these children be imposter demon children made by Longlegs to creat these crimes? In one of the recent trailers there is what seems to be a cracked open head with smoke. It looked like a child.