How about just acknowledging that a mutation's changing an allele, at best can only change whatever that gene governs, so if it's a gene for fur color the mutation is only going to affect fur color? Pretty simple it seems to me.
HBD wrote an excellent message pointing out that you are wrong, it's not simple.
Phenotypic traits depend on more than one gene. Each gene is often involved in multiple phenotypic traits.
quote: Hox genes, a subset of homeotic genes, are a group of related genes that control the body plan of an embryo along the head-tail axis. After the embryonic segments have formed, the Hox proteins determine the type of appendages (e.g. legs, antennae, and wings in fruit flies ) or the different types of vertebrae (in humans) that will form on a segment. Hox proteins thus confer segmental identity, but do not form the actual segments themselves.
Please just acknowledge that an allele changed by mutation can at best only change whatever that gene governs, so if it's a gene for fur color the mutation is only going to affect fur color.
Can't do that. It would be lying. See HBD's excellent exposition.
(Even if you were right that it could affect many traits, such a change would only affect those particular designated traits because the gene determines what those traits are.)
You'll never figure it out if you insist on avoiding real molecular genetics and stick to your fantasized version.