Genotype	Phenotype
H H	Hen feathered	Hen feathered
H h	Hen feathered	Hen feathered
h h	Hen feathered	Cock feathered

Plumage in domestic fowl is controlled by an autosomal locus whose expression is modified by the individual's sex hormones: cock feathering is longer and pointed than hen feathering.

Leghorn hh hens can be induced to produce cock feathering by removing the ovaries, indicating that female sex hormones inhibit cock feathering.