Cecisflock
The Backyard Brahmas
I am sorry, but you are mistaken. This is not a myth! I experienced this and this is true, this was confirmed by the chicks experts at Wilco as well.
Quoted from another thread. Thanks @The MoonshinerFeather sexing only works within the first few days and only works when you breed a fast feathering male over a slow feathering female.
Feather growth rate is sex linked. A fast feathering male will have two genes for it and pass one to all offspring.
The slow feathering female will only have one gene and will pass it to her sons only.
Slow is dominate so the males with feather in slower then the females.