Why not just let it be the radiation released into the atmosphere from the Infinity Stones? Why does the Quantum realm have to be involved at all?
Yes, this. As cool as reviving the cryptic "Children of the Atom" phrase for First Class was, "infinity radiation activates this one allele some humans have" is actually less stupid technobabble than "all radiation causes mutation, which is always the X-gene that gives you a random superpower, rather than causing cancer."