Hi, I've got three 4 week old Speckled Sussex chicks that I bought from a reputable hatchery. Two of the three look just like each other, while the third looks quite different. The two who match have a lot more feathers grown in, and have lighter-colored, well-speckled feathers, with some white on the chest and white bars on the underside of their wings. The third has much less feather development, especially on the tail, and the feathers are darker mahogany color, with no sign of the white wing bar and less white on the chest. White feathers are starting to come in on the third one's head, while the first two still don't have any white on their heads. They are supposed to be all pullets, but I hear that Sussex are difficult to sex, and am wondering if the odd chick out might be a rooster. Or is this just a normal variation in their coloring?