The archetypal gene of this family, yellow (y), was identified by the abnormal yellow phenotype of the adult cuticle and larval mouthparts of D.mel mutants. Yellow-like genes have been identified in insects, bacteria, fungi, and three non-insect eukaryotes. Their roles in appear to be quite divergent, and include influencing pigmentation, behaviour, and sex-specific reproductive maturation and epigenetic reprogramming. (Adapted from FBrf0212607).