MacDonald triad

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.

It should be noted that recently this Triad, developed in 1963, has been called into question by other researchers. They note that many children and teenagers set fires or harm animals for many reasons (boredom, imitation of adult punishment of household pets, exploration of a "tough guy" identity, or even feelings of frustration). It is thus difficult to know whether these variables are in fact relevant to serial murder etiology and, if so, how precisely they matter.

These three traits are now included in the Diagnostic and Statistical Manual of Mental Disorders IV-TR under conduct disorder.