The Author of the Source Story Hates Children (PROOF)
The author of the original story (Lionel Shriver) was a woman in her forty's, who decided when she was eight that she did not want children. (Source: DVD Extras Interview)
For those of you who consider Kevin to be a complete psychopath, remember that he is not a real person, but a fictional character devised by an author who said the following about children:
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"Childless at 48, I'm now old enough for the question of motherhood to have become merely philosophical. Still, I've had all the time in the world to have babies. I am married. I've been in perfect reproductive health. I could have afforded children, financially. I just didn't want them. They are untidy; they would have messed up my flat. In the main, they are ungrateful. They would have siphoned too much time away from the writing of my precious books."
http://www.theguardian.com/books/2005/sep/17/society
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So she calls them untidy and ungrateful, despite not having any! This is the equivalent of a misogynist author writing a female character, or a racist writing a minority character.
I found some of the characters to be unrealistic almost to the point of being a Lifetime Movie. For those of you looking for other movies on similar subject matter, I would suggest "400 Blows", "Precious", "Ordinary People" (troubled childhood) or "Elephant" (school massacre).