So, where did they come from I wonder?

We know that the vaxxes can shed spike proteins, is it not possible that these vaccines were shedding SV40?

The lack of link between those with polio vaccines and cancer rates is telling, although I question whether they took into account those who received the contaminated vaccines versus those who got clean shots. If the former group is much smaller than the larger group, the difference in cancer rates could be statistically insignificant on the whole, but significant specifically for this with SV40 in their shots.