thats true only if the Rooster is Heterozygous for the peacomb gene(P/p+) but if he is homozygous for it(P/P) all of the progeny will have pea combsAt best. 25% pea combed pullets... Lets say you had 10 chicks hatch. Statistically...50% will be Roos...then the other 50% will be. Pullets...of those 5 pullets. At best 2.5 or 25% will have pea combs ( because all moms have straight combs and dad has pea comb)... Soooo....it's not random its statistics
If you want 10 colored egg layers you need to hatch out 50 chicks to get the percentages to work in your favor