Tebop, its part of a background investigation-they want to know what type of person you are.  If nobody knows you-that's a heck of a lot better that if some one says, oh that is the house that has police over there several times a month, or that is the house that has a lot of crummy looking people coming and going at all hours of the night.  They will ask folks that you didn't mention in your neighborhood too.   How do I know, well I had to go for Secret and Top Secret clearances several times during my career and the FBI was extremely thorough. Oh, yes, I always got the required clearances. 

Jan