Tabby: Tabby is a dominant gene, so a cat only needs one copy of this gene in order to “show” tabby. With the tabby gene, a black cat becomes a brown tabby, a red cat becomes a red tabby, and a tortie becomes a brown-patched tabby. If a cat has two copies of the Tabby gene (homozygous tabby), then ALL offspring will have at least one copy of the Tabby gene, therefore, all offspring will be tabbies of some sort.