"Though we no longer say that some children are born bad, the facts are such, unfortunately, that a euphemism is needed. Now psychologists say that some children are born with 'difficult' temperaments—difficult for their parents to rear, difficult to socialize. I can list for you some of the things that make a child difficult to rear and difficult to socialize: a tendency to be active, impulsive, aggressive, and quick to anger; a tendency to get bored with routine activities and to seek excitement; a tendency to be unafraid of being hurt; an insensitivity to the feelings of others; and, more often than not, a muscular build and an IQ a little lower than average. All of these characteristics have a significant genetic component."
Judith Rich Harris,
author of The Nurture Assumption,
in "Why children turn out the way they do," Saturday Evening
Post, May 1999