Tim Quinn and Dicky Howett conducted research to discover the evolutionary trees of Doctor Who characters.
Dan Dare was an ancestor of the Doctor from the 1950s and P. Cushing was found to be the missing link between the First and Second Doctors.
Michael Grade's determination to "Kill the Doctor" passed to Davros which in turn passed to the Mekon, who referred to either Professor Peabody or Doctor Blasco when uttering the phrase.
Sir Hubert Guest and Brigadier Lethbridge-Stewart were discovered to be part of the same tree, as was the Doctor's TARDIS and the Anastasia. Peri Brown knew she had "evolved" from Digby, a prospect that made her shudder. (NOTVALID: Origins of Who?)