Here in the states we have a naked neck breed and they're bred to the standard and shown.
But the naked neck birds carry a gene for their naked necks. They can be bred to any chicken and pass on the gene so here we have other breeds that now come with naked necks.
Naked necks can carry one or two genes for it. If they have a patch of feathers sometimes referred to as "bowtie" they carry one copy of the gene. If they're completely naked necked they carry two copies.
A single gene naked neck will produce about 50% naked neck chicks when bred to any other chicken.
One that carries two genes for it will produce 100% naked neck chicks.
All those chicks will only carry one gene for it but then you can cross them and get about 25% chicks that carry two copies and those can be bred together for 100% true breeding naked necks.
Point is if you just like the naked neck look all you need to find is one and you can make more.