Alpha particles bouncing off gold foil in Rutherford's gold-foil experiment which developed the understanding of the structure of the atom, expanding upon Thomson's research with cathode rays.
If the mans father could not roll his tongue, then the father has a genotype of rr.
Now if the man (the son) can roll his tongue this mean he has a genotype of either RR or Rr.
Because the father has a genotype of rr, that means the son has to have at least one allele of r.
This means the genotype of the man is Rr.
The most likely cause of the observed variation is adaptation and evolution
The kidney works harder when you drink lots of water, no water = kidney failure.