now whats really interesting, is that this means we can, with the right technology, change people genetics. Interesting huh?
Not really; the RNA injected does not actually replace genetic material. It merely temporarily adds a function to the cell (though the killing of the cell by the virus normally stops it from wearing off). RNA can't replace DNA; they're two different things. Similar, but not exactly the same. In particular, the type of RNA injected is mRNA (m for messenger), which goes into ribosomes (composed of another type of RNA), where tRNA (translator, I think) assmembles amino acids based on the pattern of the mRNA. Basically. I can't remember all the little details. Also, not all viruses use RNA. Bacteria-infecting viruses actually use DNA. That does not replace the hosts DNA either, but instead splices it into the cell's original DNA.
So you're probably wondering, if bacteria-infecting viruses splice in DNA, why can't we alter those to edit our DNA? Well, that method is ineffective against us, because our DNA is held within a nucleic shell (which bacteria doesn't have). A completed strand of DNA doesn't get through that easily, and is the main problem with altering DNA of anything other than bacteria. We can, however, still do amazing stuff based on viruses. Just not everything you might think at first.