It’s unlikely that a virus could so crucially alter humanity’s collective DNA essentially overnight (it hasn’t happened yet, but never say never) but viruses do alter our DNA. They’ve been doing so for millions of years, and we wouldn’t be who we are today without them.
Sometimes… a virus will infect a germ cell, delivering its genetic material to a sperm or egg. When that happens, it’s possible for the virus’s genetic material to pass onto the offspring. Over generations, that material can become part of the host species’ genome.
Today, roughly 8 percent of the human genome is comprised of human endogenous retroviruses (HERVs), inherited from stowaway viruses.