From Wikipedia’s “MacDonald triad” (26 July 2006):
The MacDonald triad are three major personality traits in children that are said to be warning signs for the tendency to become a serial killer. They were first described by J. M. MacDonald in his article “The Threat to Kill” in the American Journal of Psychiatry.
- Firestarting, invariably just for the thrill of destroying things.
- Cruelty to animals. Many children can be cruel to animals, such as pulling the legs off of spiders, but future serial killers often kill larger animals, like dogs and cats, and frequently for their solitary enjoyment rather than to impress peers.
- Bedwetting beyond the age when children normally grow out of such behaviour.