Many years ago, a group of scientists in Cambridge discovered that certain characteristics are passed down from parent birds to their sons and not their daughters and vice versa.

Some of these characteristics are down colours and markings that can be used to identify male and female chicks when they hatch. This is a very useful characteristic for commercial or hobby producers of hybrid laying hens, it effectively halves the rearing costs since unwanted cockerels need not be grown on un-necessarily.

It was found that cocks with a genetically 'gold' plumage crossed with hens that had a genetically 'silver' plumage produced male and female chicks of different colours.

In order to get sex linkage we must mate a gold plumage cock to a silver plumage hen. The female chick will take after the sire and be the same 'gold' colour and the male chick will take after the dame and be 'silver'.

Silver Plumage is dominant to gold, but silver hens are able to transmit gold plumage to their sons.

A reverse mating (Silver Cock to Gold Hens) does not work. Silver is dominant and all of the chicks will be 'silver'. Tinted eggs are dominant over white eggs – so if either parent mated lays tinted eggs, this will be passed on to the offspring.