Genetics of Grey Factor

Summary:
Grey Factor - dominant
Normal - recessive

There are only two alleles for the grey trait: the grey factor gene and the normal gene. The grey factor gene is completely dominant to the recessive normal gene. This means that a single-factor grey looks the same as the double-factor grey. Here, we will represent the grey gene as "G" and the normal gene as "g". Therefore there are three possible genetic combinations for any budgie:

• gg - Two normal genes (homozygous) resulting in a normal budgie.
• Gg - One grey factor gene and one normal gene (heterozygous) resulting in a grey factor budgie that is genetically single-factor.
• GG - Two grey factor genes (homozygous) resulting in a grey factor budgie that is genetically double-factor.

As you can see, it only takes one grey gene for a budgie to display the grey factor. This makes this is an easy variety to breed. Grey factor creates grey-green in yellow-based budgies and grey in white-based budgies. Below are some punnet square examples of pairings. A budgie described as "grey factor," "single factor grey," or "double factor grey" can either be yellow-based (grey green) or white-based (grey).