okay I have 3 white hens and 2 brown hens, I bought them all in april on the same day so they are all same age and they turned 20 weeks old this week but only one white hen has started laying, she has laid one egg a day since, but the other 4 have not, why is that? all 3 of the white hens have dark red combs and waddles while the two brown hens dont have a waddle or comb at all thats visible...but how can that be when they are all same age? any info for me please?