Ian's Ph.D. is from the University of North Carolina at Chapel Hill (1980), and his advisor is Charles R. Baker (PhD, UCLA, 1967). At UCLA, Charles Baker was jointly advised by A. V. Balakrishnan and V. S. Varadarajan. Charles wrote to Ian in 2007: "My PhD degree was in Engineering, with a major in a program called Systems Science (which no longer exists) and minor fields in Statistics and Applied Math. The UCLA engineering school of those days required a PhD program to consist of three fields of study, with 15-18 semester hours of graduate credit in each. The PhD committees had five members, and my committee consisted of A. V. Balakrishnan as Chairman and members (listed alphabetically) Jack W. Carlyle, Paul G. Hoel, V. S. Varadarajan, and Andrew J. Viterbi. Balakrishnan was chairman of the System Science program and both Carlyle and Viterbi were Systems Science faculty members. Viterbi was a co-founder of the wireless company Qualcomm, which early on capitalized on some of the research that he conducted (and lectured on) at UCLA. Balakrishnan and Varadarajan contributed significantly to my research efforts, and both were engaged and helpful."
The "ancestors" of A. V. Balakrishnan in succession are: Ralph Phillips, T. Hildebrandt, E. H. Moore, H. A. Newton, Michel Chasles, Simeon Poisson, Joseph Lagrange, Leonhard Euler, Johann Bernoulli, Jacob Bernoulli, Gottfried Leibniz, and Erhard Weigel (PhD, University of Leipzig, 1650, academic advisor unknown).
The "ancestors" of V. S. Varadarajan in succession are: C. R. Rao, R. A. Fisher, Sir James Jeans, Edmund Whittaker, Andrew Forsyth and George Darwin (jointly), Arthur Cayley, William Hopkins, Adam Sedgwick, Thomas Jones, Thomas Postlethwaite, Stephen Whisson, Walter Taylor, Robert Smith, Roger Cotes, Isaac Newton, Isaac Barrow (Barrow's mentor was James Duport who was a classicist, but Barrow really learned his mathematics by working under Gilles Personne de Roberval in Paris and Vincenzio Viviani in Florence), Vincenzio Viviani, Galileo Galilei, Ostilio Ricci, and Niccolo Fontana Tartaglia (academic advisor unknown).
Ian's Erdos Number is 3. Two paths: Fred W. Huffer to Persi Diaconis (who is a coauthor of Paul Erdos); John H. J. Einmahl to Paul Deheuvals (who is a coauthor of Paul Erdos).
Reference: Mathematics Genealogy Project.