Why is it such a stretch for people to believe that markers are there for a reason.
Every pairing is going to alter the outcome with both sets of genetics.
The two traits TOGETHER make up the new snake, pastel + normal genes or het clown + normal gene.
Is it really that hard for people to see that the het traits alter the normal gene just as a pastel does, or any other incomplete dominant(heterozygous) trait does?
They are all heterozygous traits after all.