The superintendent of schools in Lexington, Mass., said it all started when two first-grade boys argued over who should sit where in the cafeteria. One of them punched the other several times on the playground while at least five children stood by and watched, the superintendent said. But according to a Massachusetts group that opposes gay rights, a band of first-graders singled out 7-year-old Jacob Parker for a schoolyard “beating” in retaliation for his father’s campaign to stop Estabrook Elementary School from including information about same-sex parents in its curriculum. The May 17 incident was triggered by a climate of...