Academic ancestry

According to the Mathematics Genealogy Project, my academic ancestry can be traced back through fifteen generations:

Alan J. Cain
↓			↓
Nikola Ruškuc			↓
↓		↓	↓
John M. Howie		Edmund F. Robertson
↓		↓
Graham Higman		Stewart E. Stonhewer
↓		↓
John H.C. Whitehead		?
↓
Oswald Veblen
↓
Eliakim H. Moore
↓
Hubert A. Newton
↓
Michel Chasles
↓
Simeon Poisson
↓		↓
Joseph Lagrange		Pierre-Simon Laplace
↓		↓
Leonhard Euler		Jean Le Rond d'Alembert
↓		↓
Johann Bernoulli		?
↓
Jacob Bernoulli
↓
Gottfried Leibniz
↓
Erhard Weigel
↓
?