Cyclic trend through generations of excellence, Top researchers -> Their PhD students -> Top researchers ->
This is commonly known and observed.  See the discussion of academic "family trees".  

https://en.wikipedia.org/wiki/Academic_genealogy

But I do think what you did is a little more interesting to actually pull the thesis of each person and skim it.  Not just note the big name. Very cool.  Kudos.

I think the trend occurs because more famous individuals tend to have lots of graduate students (perhaps also being pulled to fancier institutions and having access to stronger grad students).  

FYI, if you trace back almost all current "name" inorganic chemists in the US, you will find that they are "progeny" of Linus Pauling (multiple generations).  Similar trends in physical chemistry or organic chemistry or nuclear physics.  

I would imagine there would be some (but less) of the same effect in mathematics or literature or the like.  This is because big names will still have a bit more funding and just attract the stronger individuals.  But those are fields where there is less need for expensive equipment, large groups of students, etc.  (IOW, more random individual geniuses.)