When I first got my pullets and they weren't laying any eggs, a lot of people suggested that maybe I had roosters. As we know now this was not the case. My toddler-aged chicks have grown up nicely into hens.
A friend of mine was not so lucky. Mrs. Utz (the mother of my best high school friend, Sarah) started with three chicks; Patty, Little Gerri and Lucy, only to find out that Patty is really a Patrick.
I decided to do a little research on gender assignment of young poultry. I use the term research loosely. Maybe 'Google search for instant gratification of curiosity' fits better. Anyway, I came across this table which answers another question I had about the term sex links. It is kind of obvious now.