What human - ever - has "tampered with the genes" of their dog?
Obviously, genetics had not been established as a realm of scholarship in the Paleolithic Era. Nonetheless, our distant ancestors were, indeed, changing the genetic makeup of wolves/dogs by the ancient, tried-and-true process of selective breeding. The ones who stayed close to the human community; keeping the place (relatively) clean by eating the garbage; going out on hunting trips with the men and using their superior hearing and sense of smell to find game; following the women and children to protect them as they foraged for herbs and fruits; using their superior night vision and hearing to keep us safe while we slept, which allowed us to have longer periods of REM to catalog the day's new information... these were the wolves who were adopted by the tribe, while the others ended up in the stew pot.
As I noted earlier, the result of all this was an animal that looks like a wolf, but has a smaller brain requiring less precious protein in his diet, has a much weaker alpha instinct and doesn't compete with the head human to be leader of the pack, and spends a lot of time playing with the children, keeping them out from under foot, and eventually becoming a contented member of a multi-species community, protecting the cattle, goats, swine, horses and sundry other species from predators.
All these years later (there's no solid evidence to determine when the human/canine partnership began, possibly as early as 30KYA but surely by 10KYA), there are distinct differences between wolf DNA and dog DNA. They are the same species and can interbreed easily, but they are different enough to be classified as separate subspecies:
Canis lupus lupus (the wolf) and
Canis lupus familiaris (the dog).
You can call this "genetic tampering" or "selective breeding." The results are the same.