I grew up in a very small down in the middle of Missouri...no other Christopher's or Chris's in my class, but there were three of us with the exact same birthday.
The total # of kids in my grade was less than 40 (and we had one of the largest grades in school so each year they had to break us up into two classes).
When I started KPMG, there were three other Chris' in the department. Even though I use my full name, everyone seemed to find it easier to call me by my last name. Thank goodness that didn't last after I left KPMG.