Hi SDF

Only a few traits show definite simple Mendelian hereditary and are therefore controlled by a single gene. But how that gene turns into a trait is a lot more complicated. There are simple gene=>protein expressions in the body, but often times one gene regulates another, and so on, creating huge interacting 'programs' of genes. This is much harder to transfer from species to species and AFAIK hasn't been done yet, though micro-chromosome genetic engineering might enable it, if competing genes in an organism can be silenced and the proper regulatory sequences plugged in. All areas of active research.

As for gene 'patches' just recently some cancer patients were successfully treated by patching in new genes. But rearrangements of organs or limbs is probably impossible - reverting so much somatic tissue back to being pluripotent cells is probably impossible in metazoa. Limb regrowth and organ regeneration maybe possible, as well as reverting tissue cultures, but wholescale rearrangement is beyond what cells do during normal ontogeny. As a body develops the cells respond to very specific commands and sensations probably unique to that stage of life. Rewriting that sequence is well, well beyond us currently. And keeping such a mass of mobile tissue supplied with blood and nerves is nightmarishly complex. It's okay in a tiny embryo or fetus, but in an adult sized soma it's a whole other problem.

That being said there might be nanotechnological ways around such issues. If a largescale cellular scaffolding and guidance network could envelop and guide the metamorphosis, then it maybe possible. I've often imagined how a whole body might be "reprinted" using the developing "organ-printing" tissue technology, but it's a fair ways off yet.

Adam