Flipping through baseball cards in his spacious bedroom, accented with sailboat-print curtains and a chew toy left by his dog, Triscuit, Mark Fishman of Weston is the picture of a happy, well-adjusted 9-year-old.
He bounces on his bed, bemoans the record of his Little League team, and shows off his math and soccer certificates, awarded for excellence. His mother says he gets good grades and plays well with his younger brother, Jason, and little sister, Rachel.
Yet something has happened to Mark during the last two years, a strange and troubling transformation that is sweeping the elementary students of Weston like a bad case of head lice.
Mark and his classmates here are abandoning the Red Sox for the New York Yankees, shunning the Olde Towne Team in a show of rebellion that is upending this quiet community of top-notch public schools, giant homes guarded by sport utility vehicles, and rolling lawns dotted with swing sets.
Mark's parents say that most of the boys in his class, about 50 children who will enter fourth grade at the Field School this fall, are now waving the pinstriped banner, tossing out their Pedro jerseys, and cheering for Derek Jeter.
Mark, eyeing the Yankees calendar and license plate on the wall, puts the figure closer to 65. The girls in his class, he sniffs, support the Red Sox.
"I think I just got on to this big Yankee chain, because all my school friends are Yankees fans," he said, backed by his friend, Andrew Bromfield, 9, also a Yankees fan. "I like how they always win and they have good players."
Mark said he has given away his Red Sox shirts and hats and is planning to sell a Sox souvenir baseball, perhaps for a $5 profit. He is teaching Triscuit to bark "Yankees," he said.
Mark's defection to the Evil Empire has not gone over well with mom and dad.
"We're horrified. We kept thinking this would go away, that this was just a phase," said his mother, Laurie Fishman, a transplanted New Yorker who now roots for the Red Sox. "We didn't realize the extent of it, until we talked to other parents and realized more and more boys are Yankees fans."
Laurie Fishman, a pediatrician, says she never saw the signs of Yankees fever taking root in her community.
"All of a sudden this wave flipped over the class, and they all became Yankees fans," she said.
Mark's father, Steven Fishman, also a doctor, sounds resigned. "We may be stuck with a Yankees fan, possibly for life," he said.
The Fishmans are not alone.
"My parents think I might change, but I don't think so," said James Goulart, 9, who describes himself as "probably one of the two biggest Yankee fans going into the fourth grade."
The Red Sox-Yankees rivalry boiled over into on-field violence during a recent series at Fenway, but Donna Goulart, James's mother, said she trusted that her boy's pinstripe passion would remain in check.
"James is a gentle soul," she said. "He has a good grip on his emotions."
Town sports officials are not taking the insurgency as lightly. The 15-member board that controls Weston Little League voted in March to ban Yankees as a team name, said the league's commissioner, Billy Burchard. In May, Burchard announced the ban to about 1,000 parents and fans gathered at Little League opening day on Weston's town green.
"There was a big cheer and a laugh, and that was the end of it," Burchard said.
Harold Hestnes, a member of Weston's Board of Selectmen, said he disagreed with the local Yankees ban. He said beleaguered young Sox fans might benefit from the opportunity to taste championship glory.
"It seems rather strange to deprive kids of the ability to relate to a winner, which is what the Yankees have been," Hestnes said, adding that he is a Red Sox fan.
Dr. Anita Bohensky, a New York child psychologist, said she was puzzled by the Weston children's behavior and would need to interview them to render a proper analysis.
She speculated that the children might be exhibiting aspects of early adolescent rebellion or emulating an admired older peer who is a Yankees fan. She said it was unusual for 9-year-olds to rebel against their parents in this way.
"Kids of that age typically do what their parents are doing," she said. "Maybe kids don't want to be associated with a loser."
Mark Fishman said his own infatuation with the Bronx Bombers began two years ago, when his Little League team was the Yankees. Slowly and then more boldly, he rooted for the Major League team.
Mark said Weston's ban on the Yankees name would only embolden his comrades.
"I just think it makes Yankees fans frustrated," he said, "and they'll try to convince more people to be Yankees fans."
For now, the Fishman household has become a miniature, more placid version of the legendary intercity rivalry. Like Yankee fans everywhere, Mark doesn't mind the back and forth.
"They sort of tease me a little bit," Mark said, "but I think I'm the one who should be teasing them."