It's definitely an unknown until we get more info. It's clear that MC's metagene is transferred from MC to a donor, merges with their metagene DNA, and "transmits" their power back to MC if they're in an appropriately aroused state. What's unclear is in what manner that affects the donor DNA long-term, if MC's metagene DNA needs to remain there to continue to transmit their power back to him (for example, if a donor dies, does MC lose their power?), and what happens if MC's metagene DNA tries to bind to someone without powers. There's hints that it might do more than just transfer to MC, but it's still far from clear.
Though on that note, biologically speaking, if the merged DNA functions like normal DNA, it would continue to replicate within the donor as new cells are created and potentially even propagate into any children they have if it merged into gamete DNA.