As the math genealogy database itself points out,
For the earlier periods the
advisor/advisee relationship may not have been nearly so formal as it is in
modern times. Thus, the links shown for those periods may reflect a
mentor/student circumstance that is somewhat different than the links for more
The case of Lagrange is a particular blatant example. Lagrange was largely self taught; the fact that he corresponded with Euler about his results, and that Euler supported his career does not mean, by modern standards, that Euler was Lagrange's Ph.D. advisor.
But whether or not I can count Euler as my "ancestor" in any formal sense makes not the slightest difference: climbing up the family tree leads nowhere -- just for show.
Back to my Home page, or to my family tree.