Fading Violet Chinchillas

Somehow Fading Violet snuck into my Blue Diamond lines. I am starting to see some of my Violet sapphire carriers fade around the nose, ears and tail. Some people believe that it is a recessive gene. I am starting to feel that it is an incomplete dominant that is influenced by other things. For example, a female that I linebred to her sire should have had extreme fading or at least faded by the time her sire and dam did. Instead, she didn't start to fade until 3.5 years of age and the fading is minimal. Some of her full siblings have never faded and others as young as a year have already started. I am now seeing it in a few Sapphire animals. My conclusion is that it can be passed on by one parent if certain criteria are met, it is questionably accumulative but not sure what factors cause it to appear earlier or later or not at all.