The authors of the paper suggest UV radiation, which indeed damages DNA, is responsible for the effect. Note that Earth's atmosphere, in particular ozone layer, filters out most of UV radiation above 10 eV. In TGD Universe one must however worry also about the well-being of magnetic body besides that of the biological body so that life becomes really difficult with the hedonistic attitude of modern man. My nightmare is that the people in future - thanks to TGD - must also worry how good-looking their magnetic bodies are!
Could the primary damage occur for the magnetic body receiving an increased radiation dose during magnetic storms induced by the the solar wind shock waves accompanying the sunspot activity. The solar wind shock wave would be a slap against magnetic face.
The incoming radiation would be physical violence but at the level of magnetic bodies with onion like structure having size scales even larger than Earth size scale (Schumann resonance). This violence would deform the shape of the magnetic body, in particular change the thickness of the flux tubes and in this manner affect magnetic field strengths and cyclotron frequencies crucial for the resonant communications with the biological body. The communications between biological and magnetic body could suffer and sensory input to and motor actions of the magnetic body would be disturbed. This could even lead to a loss of consciousness as is indeed reported to happen sometimes during auroras known to involve magnetic reconnections induced by solar wind at the dark side of the Earth. A possible experimental signature would be the direct effects of magnetic storms on EEG and also direct negative effects such on general well-being.
I have a personal experience about very unpleasant effects possibly caused by magnetic storm during a travel in Sweden. Suddenly I got a horrible migraine like headache. We were guessing for possible reasons and someone noticed that magnetic storms were occurring just at that time. Somehow me and my magnetic body regarded this explanation more feasible than the other ones.
So the question is whether one could one feel the magnetic storms directly - for instance as pains projected to some biological body part? If the layers of the magnetic body carry maps of the biological body parts as I have proposed, this might be the case. The effect would be the analog of projected pain. This projection would occur very generally. For instance, the very unpleasant feeling near a precipice could be due to the actual motion of magnetic body mimicking the falling down from the precipice. Also various out-of-body experiences such as levitation could take place at the level of magnetic body in the virtual magnetic world representing also the environment.
Note that from this it is not a long way to the speculation that the positions of planets dictating the periodically occurring mutual interactions of their magnetic bodies could affect the life cycle so that your birth day would matter and the basic idea behind horoscope might make sense although horoscopes as such would not!