Since the paints only have “genetic info to come” in their description, I’m relatively certain it’s a new mutation. If it were a combination of known mutations there would probably be a known genotype already considering that Porter has had them for a couple of years by now. I don’t think it’s the spotting gene, because the spotting gene is a recessive gene and we know the paints don’t breed true. Additionally they don’t have the brown head spot. The only way for a recessive gene to express with one copy is if the other gene is also recessive. There are 4 variations we know are related to the paints: white, paint, grizzled paint, and tuxedo. Under the circumstances that the paint gene is recessive and resides on the second locus and was pt//c, it would produce 25% white(c//c), 25% tuxedo(pt//pt), and 50% paint(pt//c), which lines up perfectly with what’s known so far. That’s my reasoning behind why I think it’s a new mutation on the color locus, and not the spotting locus.