Both. Some of the more infamous ones today have an explicitly religious slant, but by and large they recycle ideas about children that were first made popular by psychologists (although the religious writers tend to call psychology evil and vice versa). The books tell parents, mostly mothers, that children must be made to know their place when they are still infants, not ask for things, be completely predictable, submit to the parent in all things, etc., or they will be very bad people when they grow up, and it will be 100 percent the parent's fault. This kind of thing tends to stick with a person.