Alleles are not well understood among ball python breeders yet. If a cross line leucistic bred to a normal ever did produce a leucistic we would need a new theory. But I don't expect that to happen. The theory that fits all the breedings I've heard about so far is that lesser and Mojave are two different versions of the same gene (alleles) so each baby would only get one or the other version from the leucistic parent. When Morph King bred them to lots of normals I heard they only got the two grandparent types and no leucistics and no normals which is consistent with the allele theory.

However, there is currently on kingsnake a paradox ivory that shouldn't be. It's from ivory X normal. One theory on paradox is that it's two siblings that merge into one (a chimera). Under that theory the paradox shouldn't show a type that couldn't be in the clutch. An ivory X normal should not be able to produce an ivory. So something gives. My bet is it has something to do with the paradox. Someone (maybe here) pointed out some different types of chimeras and some might include two sperm. Maybe some how two yellow belly sperm fertilized the same egg and somehow made some parts that are ivory like. Or maybe ivorys can be made by combos of different related genes and not just alleles of a single yellow belly gene.