"We still do not know the real long term truth of solar radiation. There is not enough scientific historical data. "
I'd be intrigued to hear your explanation of that statement, having a scientific background and a son who is a physicist.
There IS quite a lot that we don't understand about our sun (like why the solar corona is so hot), but there is also quite a lot that we DO understand. The biological effects of solar UV are reasonably well understood now and there is a fairly good historical record of solar activity from a variety of sources going back a fairly long way.
We know that the Sun is a middle-aged G-type main-sequence star that has not changed dramatically for around 4 billion years and is likely to remain fairly stable for another 5 billion, though there will be periods of increased or decreased solar activity (see Maunder minima, etc.).
Global warming is an undeniable fact and we are at least reasonably sure that some of this is anthropogenic and that we can make it worse.
No, we don't know "..the real long term truth of solar radiation.." because we don't know enough about small-scale solar dynamics.
Trying to equate this with a highly variable and selective "syndrome" with protean and mainly anecdotal manifestations for which the evidence base is several orders of magnitude smaller is, I submit, unreasonable to say the least.