The thousands of men expelled from the Irving-based Boy Scouts of America on suspicion of molesting children came from all walks of life — teachers and plumbers, doctors and bus drivers, politicians and police officers. They ranged in age from teenagers to senior citizens and came from troops in every state. As the Scouts have long said, the files suggest no single profile of a predator. But a close look at nearly 1,900 confidential files opened between 1970 and 1991 revealed a pattern: Many suspected molesters engaged in what psychologists today call “grooming behavior,” a gradual seduction in which predators...