Parent specifically stated DNA viruses. From your article:
> Most of these viral genes come from retroviruses, RNA viruses that insert DNA copies of their own genes into our genomes when they infect cells. HHV-6 is unique because it is the only known human DNA herpesvirus that integrates into the human genome and can be routinely inherited.
> Most of these viral genes come from retroviruses, RNA viruses that insert DNA copies of their own genes into our genomes when they infect cells. HHV-6 is unique because it is the only known human DNA herpesvirus that integrates into the human genome and can be routinely inherited.