By Bob Brody The borough of Fair Lawn has turned 100 years old. What’s the big deal about this centennial birthday? Fair Lawn happens to be my hometown. I grew up in Fair Lawn, from ages 2 to 23, between 1954 and 1975. Our family of four had emigrated from the Bronx to live in an 1,800-square-foot split-level colonial house on a quarter-acre plot. I never suspected the experience would teach lessons that I still carry with me today. A suburb in Bergen County, with a population of 35,000, Fair Lawn is about 12 miles west of Manhattan. The 5.2-acre municipality — what realtors still call a “bedr…