One way you can tell if your white chick is dominant or recessive is the down color. Dominant white chicks are usually yellow, where recessive ones are smokey like a splash chick, only the feathers will grow in white. I've had this with both my white Jersey Giants and some Silkie x EE crosses. Dominant white birds will also usually have spots of red or black on them, since the gene is considered "leaky". I believe Leghorns and a few other white breeds are based on recessive white because it's a clean white.