From the ArcaMax Publishing, James Dobson - Focus on the Family Newsletter:
http://www.arcamax.com/news/dobsonparenting/s-641564-781000
SIBLING RIVALRY CAN BE SPARKED BY PARENTS
QUESTION: If jealousy between kids is so common, then how can parents
minimize the natural antagonism children feel for their siblings?
DR. DOBSON: It's helpful to avoid circumstances that compare them
unfavorably with each other. They are extremely sensitive to the
competitive edge of their relationship. The question is not "How
am I doing?" it is "How am I doing compared with John or
Steven or Marion?" The issue is not how fast I can run, but who
crosses the finish line first. A boy does not care how tall he is; he
is vitally interested in who is tallest.
Each child systematically measures himself against his peers and is
tremendously sensitive to failure within his own family. Accordingly,
parents should guard against comparative statements that routinely
favor one child over another.
Perhaps an illustration will help make the case. When I was about ten
years old, I loved to play with a couple of dogs that belonged to two
families in the neighborhood. One was a black Scottie who liked to
chase and retrieve tennis balls. The other was a pug bulldog who had a
notoriously bad attitude. One day as I was tossing the ball for the
Scottie, it occurred to me that it might be interesting to throw it in
the direction of the ol' grouch. It was not a smart move. The ball
rolled under the bulldog, who grabbed the Scottie by the throat when
he tried to retrieve it. It was an awful scene. Neighbors came running
as the Scottie screamed in pain. It took ten minutes and a garden hose
to pry the bulldog's grip loose, and by then the Scottie was almost
dead. He spent two weeks in the hospital, and I spent two weeks in
"the doghouse." I regret throwing that ball to this day.
I have thought about that experience many times and have begun to
recognize its application to human relationships. Indeed, it is a very
simple thing to precipitate a fight between people. All that is
necessary is to toss a ball, symbolically, under the more aggressive
of the two and prepare for the battle that ensues. This is done by
repeating negative comments one has made or by baiting one in the
presence of the other. It can be accomplished in business by assigning
overlapping territory to two managers. They will tear each other to
pieces in the inevitable rivalry. Alas, it happens every day.
This principle is also applicable to siblings. It is remarkably easy
to make them mortal enemies. All a parent must do is toss a ball in
the wrong direction. Their natural antagonism will do the rest.