Genetics....what gene and from whom determines visual sexing?

[kubotafoot]

Some breeds can be easily sexed at birth due to different feather colors, especially on the head. Which bird carries the gene (male. Or female?) for this and do you need to breed pure to have this happen or will it be dominant in a cross breeding?

 

[Pyxis]

Well, some breeds are autosexing, and those are pure breeds that you can tell the different genders at hatch, like the Legbar for example. Some other breeds in certain colors can be autosexing too. Barred plymouth rocks, for example, can be sexed based on the head spot and leg wash if you know what you're looking for, thanks to how the barred gene works. Welsummers can similarly be sexed by the pattern of their down, with females having 'crisper' markings and darker 'eyeliner' than the males. In these breeds it's not really the male or female that carries a special gene for making the chicks autosexing.

Then there are sex-linked crosses. This only works one time, by crossing specific parent birds, and the trait doesn't pass down. There are a couple ways to make crosses like this. One is to use the barring gene, and these are called black sex links. The other is to make red sex links, and this uses the gold and silver color genes. If you want to learn about this, this post is a very good rundown.