I don't see how a vet lets her know the genetics of an animal? Malocclusion is a genetic illness. If your chins parents or grandparents or great grandparents have it, s/he can have it. They may not even be old enough to have developed the condition yet. If your vet doesn't have detailed, extensive pedigrees for both chins and claims to know whether htey 'carry' malocclusion they're lying.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry