There are multiple mechanisms in Nature for swapping and splicing DNA - bacterial, viral and in our own cells. The latter mechanism is activated by nCoV-2, which creates vampire cells. Human cells have a primordial mechanism to grow a pseudopod that penetrates neighbor cells and transfers DNA without going into the surrounding fluid, by-passing all immune responses. This has been observed for the first time in COVID microphotographs.
This DNA swapping and splicing has achieved a dynamic equilibrium in the ecosystem after running septillions of genetic experiments per second for the last 3.5 billion years. I don't believe that humans will ever be able to unravel the complexities of genetics as the solar system and even the Universe will not last long enough for us to observe a tiny fraction of this historical "database".
It is IMPOSSIBLE to test the safety of genetic manipulations, because they can be combined to create a genocidal pathogen decades after release into the environment.