Say someone had two sister Houdan chicks, about 9 weeks old. These hypothetical chicks still peep, and there haven't been any major distinguishing features between the two. Their crests might be a little different, but one isn't anymore outright roo-ish than the other. Well, say this person noticed today that one of these "pullets" is just starting to get the tiniest bit of red splotching in the comb and wattle area. Should said person assume that this chick might very well be a cockerel? Do siblings generally develop at the same rate?