Blue color depends on more than one visible trait

The Blue Andalusian's dark feather edging around a diluted blue field has been investigated through experimental breeding. A 1988 study crossed Blue Andalusian and Gold-Laced Wyandotte bantams to examine the inheritance of the laced pattern. It identified extended-black background and a heterozygous blue dilution factor as part of the Andalusian stock's genetic description.

The result makes an important distinction: changing dark pigment to blue and arranging dark pigment around a feather are different components of the finished pattern. A bird that inherits blue dilution is not automatically a well-laced Andalusian. The authors interpreted their second-generation patterned birds through a proposed combination of color and pattern factors. These were conclusions about experimental stock, not a DNA identity test for every bird currently sold under the breed name.