RNA shouldn't be in the expressing mix at all, unless I'm misremembering my bio. Don't worry about anything but the plain DNA, everything else is for getting it from the strand to the skin.
I totally understand what you're asking, I tried to ask it before on a different topic, and I believe it boils down to "modifiers." You are only looking at ONE allele, one small (relatively) section of code, that says "be A(vy)." That will give you a basis to run with. Next up comes all the rest of the DNA that will affect how your final mouse comes out; there are all sorts of "on/off" switches rampant in DNA, something that seems completely unrelated could turn off some little section that makes your color look redder in mouse A than mouse B, and that's inheritable too. Therefore, selection is inheriting the small, important modifiers alongside the big, basic genes.
I hope I helped, hopefully I didn't miss your point entirely! XD (I am AWFULLY tired though, heh)
I totally understand what you're asking, I tried to ask it before on a different topic, and I believe it boils down to "modifiers." You are only looking at ONE allele, one small (relatively) section of code, that says "be A(vy)." That will give you a basis to run with. Next up comes all the rest of the DNA that will affect how your final mouse comes out; there are all sorts of "on/off" switches rampant in DNA, something that seems completely unrelated could turn off some little section that makes your color look redder in mouse A than mouse B, and that's inheritable too. Therefore, selection is inheriting the small, important modifiers alongside the big, basic genes.
I hope I helped, hopefully I didn't miss your point entirely! XD (I am AWFULLY tired though, heh)