Wait, so a -30 dBm signal (pretty strong) will induce something like 7mV across a 5 cm antenna. Your cell nuclear is up to 10 microns wide. That's 1.4 microvolts. I'm having a really hard time believing that a 1.4 uV potential across any molecule at STP can have a measurable effect without a lot of energy going into amplifying the signal.
Energy doesn't scale with distance in that way, with quantum mechanics. A "mismatch in size" (roughly speaking) will result in a different quantum efficiency, not a lowered energy, and also keep in mind that DNA is a highly coiled molecule so the resonance frequency could be deceptive. The straightened length of DNA in a cell is on the length order of meters. (Though that doesn't mean that it will resonate with meter long waves, it will have a higher efficiency with wavelengths much longer than a micron)
