There are a lot of Norman Bates' around, and many more children that just hate their parents, but it's severe mental illness along with a dysfunctional mother-child relationship that has this happen most times. Like Norma Bates, a twisted so-dependence has the child too dependent on the mother, which turns to anger in puberty. These relationships usually have abuse of some sort, along with over protection, not allowing the child to be their own selves, or to socialize. It's usually in a home where the father isn't doing much, dominated by the mother, or absent entirely. The ones that kill look at it as a liberation from a prison environment. Happens often in Thailand, a lot involving parricide, where an abused child just goes off after suffering for years the abuse from his parents, or never taught how to handle anger without violence. Spoiling also has this happen. The lack of enough mental care facilities and that loss of face has many not seeking help here, until this happens. Domestic violence here isn't looked at the same as it is in the west, often ignored by police until the fatal episode.
