SOMETIME back in 2000, Allen S. Rout, a systems programmer from Gainesville, Fla., posted a few photos of his 5-month-old son, Stephen, on his personal Web site. They were the kind of photos that every parent takes, but one in particular stood out: Stephen wearing a pair of red overalls, smiling in a crib. “We’re really blessed,” Mr. Rout wrote as the caption. “Stephen is an amazingly happy baby.”