Complex sentence: Buckskins should not be confused with dun-colored horses, which have another type of dilution gene other than the creme gene, and always have primitive markings (shoulder blade stripes, dorsal stripe, zebra stripes on legs, webbing).
Split into simpler sentences: Buckskins should not be confused with dun-colored horses, which have another type of dilution gene, not the creme gene. Duns always have primitive markings (shoulder blade stripes, dorsal stripe, zebra stripes on legs, webbing).