Traditional wisdom holds that sibling rivalry results from children trying to obtain a parent's attention. However, evidence would suggest this to be an overly simplistic model for the phenomenon. Siblings compete for everyone's attention, including a baby's.
Mrs. Snark has big ears and overhears the damnedest conversations come out of the back of her minivan. The following took place while Mrs. Snark was driving the Snark boys to a sleepover at a friend's house. Mr. Snark was not present.
Oldest Snark Son: "Miss Bear, who's the bad brother?"
Miss Bear points to the Younger Snark Son. "Bad boy."
The boy in question dissolves into laughter, shouting a protest. "Hey!"
Mrs. Snark snickers. "Oh man, sold out by a baby."
Younger Snark Son tries to counter. "Miss Bear, who's good?"
Miss Bear: "Mommie!"
Oldest Snark Son: "Miss Bear, who's your favorite?"
Miss Bear: "Dada!"