Hens are much more common than males.
Lightback Zebra Finches are less commonly available in most locations but are actually a split from the same genetic pool as CFW's. CFW and Lightback are sexlinked, recessive color mutations that genetically track with the X-chromosone of each bird. XY is a chromosone pair for a female. The mother bird determines the sex of all her offspring based on whether she passes on the X or Y chromosone of the sex gene pair. Male CFW Zebra Finches must inherit some form of the trait from both their mother and their father in order to display the trait.