While researching La Llorona and vampiresses, I noticed that lots of cultures have predominantly female monsters that use deception to prey on families. Lamia that prey on young men and children, deer women that seduce and kill young men, incubi that seduce and impregnate young women, aswang that prey on children and pregnant women, revenants of stillbirths and women who died in childbirth, mothers that seek vengeance for lost children or treasonous husbands, demonesses that cause miscarriage and stillbirth, ghouls or aswang that consume dead relatives, mysterious wives that turn out to be ghouls or aswang, mysterious husbands that turn out to be alligator men, mullo and strigoi that target former family, etc.
All of these monsters revolve around a common theme of losing family, particularly in ways that pervert the typical growth of family. Children die in the womb, at birth, or before adolescence. Spouses, adolescents and young adults are seduced away and either killed or defiled, even forced to bear demonic offspring. Mothers die in pregnancy or childbirth. The deceased are desecrated or return from the grave. Loved ones turn out to have been literal monsters the whole time.
Why is this such a common and enduring theme around the world? Why are the patterns so regular?